From e2bd690c0c1bcf4fd9e1cb057a2ea10136c4190d Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Wed, 1 Jan 2025 10:41:49 +0000
Subject: [PATCH 01/13] Move [features] section up Cargo.toml

---
 Cargo.toml | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 57fe2274..e2241b32 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,6 +11,13 @@ repository = "https://github.com/rust-random/getrandom"
 categories = ["os", "no-std"]
 exclude = [".*"]
 
+[features]
+# Implement std::error::Error for getrandom::Error and
+# use std to retrieve OS error descriptions
+std = []
+# Unstable feature to support being a libstd dependency
+rustc-dep-of-std = ["dep:compiler_builtins", "dep:core"]
+
 [dependencies]
 cfg-if = "1"
 
@@ -70,13 +77,6 @@ js-sys = { version = "0.3.75", default-features = false }
 [target.'cfg(all(getrandom_backend = "wasm_js", target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))'.dev-dependencies]
 wasm-bindgen-test = "0.3"
 
-[features]
-# Implement std::error::Error for getrandom::Error and
-# use std to retrieve OS error descriptions
-std = []
-# Unstable feature to support being a libstd dependency
-rustc-dep-of-std = ["dep:compiler_builtins", "dep:core"]
-
 [lints.rust.unexpected_cfgs]
 level = "warn"
 check-cfg = [

From d143e98ac36591ad7298f200e99c461b5899b46b Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Wed, 1 Jan 2025 11:19:08 +0000
Subject: [PATCH 02/13] Add Rustix feature flag

Size of a dependency's Cargo.lock: 33 -> 29
---
 .github/workflows/tests.yml | 3 +++
 Cargo.toml                  | 8 ++++++--
 README.md                   | 2 +-
 src/backends.rs             | 2 +-
 4 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 673fd370..fe41178b 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -59,6 +59,9 @@ jobs:
       - env:
           RUSTFLAGS: -Dwarnings --cfg getrandom_backend="linux_rustix"
         run: cargo test --target=${{ matrix.target }} --features=std
+      - env:
+          RUSTFLAGS: -Dwarnings --cfg getrandom_backend="linux_rustix"
+        run: cargo test --target=${{ matrix.target }} --features=rustix,std
       - env:
           RUSTFLAGS: -Dwarnings --cfg getrandom_test_linux_fallback
         run: cargo test --features=std
diff --git a/Cargo.toml b/Cargo.toml
index e2241b32..31757c3d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,6 +18,10 @@ std = []
 # Unstable feature to support being a libstd dependency
 rustc-dep-of-std = ["dep:compiler_builtins", "dep:core"]
 
+# Optional backend: linux_rustix
+# This flag only enables the backend; to use it you also need: getrandom_backend=linux_rustix
+rustix = ["dep:rustix"]
+
 [dependencies]
 cfg-if = "1"
 
@@ -26,12 +30,12 @@ compiler_builtins = { version = "0.1", optional = true }
 core = { version = "1.0", optional = true, package = "rustc-std-workspace-core" }
 
 # linux_android / linux_android_with_fallback
-[target.'cfg(all(any(target_os = "linux", target_os = "android"), not(any(target_env = "", getrandom_backend = "linux_rustix", getrandom_backend = "custom"))))'.dependencies]
+[target.'cfg(all(any(target_os = "linux", target_os = "android"), not(any(target_env = "", getrandom_backend = "custom"))))'.dependencies]
 libc = { version = "0.2.154", default-features = false }
 
 # linux_rustix
 [target.'cfg(all(any(target_os = "linux", target_os = "android"), any(target_env = "", getrandom_backend = "linux_rustix")))'.dependencies]
-rustix = { version = "0.38.38", default-features = false, features = ["rand"] }
+rustix = { version = "0.38.38", default-features = false, features = ["rand"], optional = true }
 
 # apple-other
 [target.'cfg(any(target_os = "ios", target_os = "visionos", target_os = "watchos", target_os = "tvos"))'.dependencies]
diff --git a/README.md b/README.md
index 7ece9ecf..71b1d561 100644
--- a/README.md
+++ b/README.md
@@ -79,7 +79,7 @@ of randomness based on their specific needs:
 | Backend name      | Target               | Target Triple            | Implementation
 | ----------------- | -------------------- | ------------------------ | --------------
 | `linux_getrandom` | Linux, Android       | `*‑linux‑*`              | [`getrandom`][1] system call (without `/dev/urandom` fallback). Bumps minimum supported Linux kernel version to 3.17 and Android API level to 23 (Marshmallow).
-| `linux_rustix`    | Linux, Android       | `*‑linux‑*`              | Same as `linux_getrandom`, but uses [`rustix`] instead of `libc`.
+| `linux_rustix`    | Linux, Android       | `*‑linux‑*`              | Same as `linux_getrandom`, but uses [`rustix`] instead of `libc`. Requires feature `rustix`.
 | `rdrand`          | x86, x86-64          | `x86_64-*`, `i686-*`     | [`RDRAND`] instruction
 | `rndr`            | AArch64              | `aarch64-*`              | [`RNDR`] register
 | `esp_idf`         | ESP-IDF              | `*‑espidf`               | [`esp_fill_random`]. WARNING: can return low-quality entropy without proper hardware configuration!
diff --git a/src/backends.rs b/src/backends.rs
index f7b720f5..f580aca5 100644
--- a/src/backends.rs
+++ b/src/backends.rs
@@ -13,7 +13,7 @@ cfg_if! {
     } else if #[cfg(getrandom_backend = "linux_getrandom")] {
         mod linux_android;
         pub use linux_android::*;
-    } else if #[cfg(getrandom_backend = "linux_rustix")] {
+    } else if #[cfg(all(feature = "rustix", getrandom_backend = "linux_rustix"))] {
         mod linux_rustix;
         pub use linux_rustix::*;
     } else if #[cfg(getrandom_backend = "rdrand")] {

From ef12a32661bf6e4d182e113fa70893ff3c5bc61c Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Wed, 1 Jan 2025 16:48:19 +0000
Subject: [PATCH 03/13] Use Rustix by default on Linux/Android with
 features=rustix

---
 Cargo.toml      | 5 +++--
 src/backends.rs | 3 +++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 31757c3d..640ece13 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,7 +19,8 @@ std = []
 rustc-dep-of-std = ["dep:compiler_builtins", "dep:core"]
 
 # Optional backend: linux_rustix
-# This flag only enables the backend; to use it you also need: getrandom_backend=linux_rustix
+# This flag enables the backend and uses it by default on Linux/Android.
+# The backend may still be overridden by setting getrandom_backend.
 rustix = ["dep:rustix"]
 
 [dependencies]
@@ -34,7 +35,7 @@ core = { version = "1.0", optional = true, package = "rustc-std-workspace-core"
 libc = { version = "0.2.154", default-features = false }
 
 # linux_rustix
-[target.'cfg(all(any(target_os = "linux", target_os = "android"), any(target_env = "", getrandom_backend = "linux_rustix")))'.dependencies]
+[target.'cfg(all(any(target_os = "linux", target_os = "android")))'.dependencies]
 rustix = { version = "0.38.38", default-features = false, features = ["rand"], optional = true }
 
 # apple-other
diff --git a/src/backends.rs b/src/backends.rs
index f580aca5..55ab3ef8 100644
--- a/src/backends.rs
+++ b/src/backends.rs
@@ -55,6 +55,9 @@ cfg_if! {
     ))] {
         mod getrandom;
         pub use getrandom::*;
+    } else if #[cfg(all(feature = "rustix", any(target_os = "android", target_os = "linux")))] {
+        mod linux_rustix;
+        pub use linux_rustix::*;
     } else if #[cfg(any(
         // Rust supports Android API level 19 (KitKat) [0] and the next upgrade targets
         // level 21 (Lollipop) [1], while `getrandom(2)` was added only in

From 217483b66369264a56753468ef18499ed3cde6d4 Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Wed, 1 Jan 2025 17:12:27 +0000
Subject: [PATCH 04/13] Add JS feature flag

Size of a dependency's Cargo.lock: 29 -> 16
---
 .github/workflows/tests.yml |  5 ++---
 Cargo.toml                  | 15 ++++++++++-----
 README.md                   | 11 ++++++-----
 src/backends.rs             | 22 +++++++++++++---------
 src/error.rs                |  2 +-
 tests/mod.rs                |  2 +-
 6 files changed, 33 insertions(+), 24 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index fe41178b..a104d5f6 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -241,15 +241,14 @@ jobs:
           - {
               description: Web,
               version: stable,
-              flags: -Dwarnings --cfg getrandom_backend="wasm_js",
-              args: --features=std,
+              args: '--features=std,js',
             }
           - {
               description: Web with Atomics,
               version: nightly,
               components: rust-src,
               flags: '-Dwarnings --cfg getrandom_backend="wasm_js" -Ctarget-feature=+atomics,+bulk-memory',
-              args: '--features=std -Zbuild-std=panic_abort,std',
+              args: '--features=std -Zbuild-std=panic_abort,std,js',
             }
     steps:
       - uses: actions/checkout@v4
diff --git a/Cargo.toml b/Cargo.toml
index 640ece13..c3c46480 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -23,6 +23,11 @@ rustc-dep-of-std = ["dep:compiler_builtins", "dep:core"]
 # The backend may still be overridden by setting getrandom_backend.
 rustix = ["dep:rustix"]
 
+# Optional backend: wasm_js
+# This flag enables the backend and uses it by default on wasm32 with unknown OS.
+# The backend may still be overridden by setting getrandom_backend.
+js = ["dep:wasm-bindgen", "dep:js-sys"]
+
 [dependencies]
 cfg-if = "1"
 
@@ -75,11 +80,11 @@ wasi = { version = "0.13", default-features = false }
 windows-targets = "0.52"
 
 # wasm_js
-[target.'cfg(all(getrandom_backend = "wasm_js", target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))'.dependencies]
-wasm-bindgen = { version = "0.2.98", default-features = false }
-[target.'cfg(all(getrandom_backend = "wasm_js", target_arch = "wasm32", any(target_os = "unknown", target_os = "none"), target_feature = "atomics"))'.dependencies]
-js-sys = { version = "0.3.75", default-features = false }
-[target.'cfg(all(getrandom_backend = "wasm_js", target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))'.dev-dependencies]
+[target.'cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))'.dependencies]
+wasm-bindgen = { version = "0.2.98", default-features = false, optional = true }
+[target.'cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none"), target_feature = "atomics"))'.dependencies]
+js-sys = { version = "0.3.75", default-features = false, optional = true }
+[target.'cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))'.dev-dependencies]
 wasm-bindgen-test = "0.3"
 
 [lints.rust.unexpected_cfgs]
diff --git a/README.md b/README.md
index 71b1d561..d1b54a31 100644
--- a/README.md
+++ b/README.md
@@ -83,7 +83,7 @@ of randomness based on their specific needs:
 | `rdrand`          | x86, x86-64          | `x86_64-*`, `i686-*`     | [`RDRAND`] instruction
 | `rndr`            | AArch64              | `aarch64-*`              | [`RNDR`] register
 | `esp_idf`         | ESP-IDF              | `*‑espidf`               | [`esp_fill_random`]. WARNING: can return low-quality entropy without proper hardware configuration!
-| `wasm_js`         | Web Browser, Node.js | `wasm32‑unknown‑unknown`, `wasm32v1-none` | [`Crypto.getRandomValues`]
+| `wasm_js`         | Web Browser, Node.js | `wasm32‑unknown‑unknown`, `wasm32v1-none` | [`Crypto.getRandomValues`]. Requires feature `js`.
 | `custom`          | All targets          | `*`                      | User-provided custom implementation (see [custom backend])
 
 Opt-in backends can be enabled using the `getrandom_backend` configuration flag.
@@ -113,17 +113,18 @@ the `wasm32-unknown-unknown` target (i.e. the target used by `wasm-pack`)
 is not automatically supported since, from the target name alone, we cannot deduce
 which JavaScript interface should be used (or if JavaScript is available at all).
 
-Instead, *if the `wasm_js` backend is enabled*, this crate will assume
+Instead, *if the `js` feature is enabled*, this crate will assume
 that you are building for an environment containing JavaScript, and will
 call the appropriate Web Crypto methods [described above](#opt-in-backends) using
-the [`wasm-bindgen`] toolchain. Both web browser (main window and Web Workers)
+the [`wasm-bindgen`] toolchain (with or without using `getrandom_backend=wasm_js`).
+Both web browser (main window and Web Workers)
 and Node.js (v19 or later) environments are supported.
 
 To enable the `wasm_js` backend, you can add the following lines to your
 project's `.cargo/config.toml` file:
 ```toml
-[target.wasm32-unknown-unknown]
-rustflags = ['--cfg', 'getrandom_backend="wasm_js"']
+[dependencies]
+getrandom = { version = "0.3", features = ["js"] }
 ```
 
 ### Custom backend
diff --git a/src/backends.rs b/src/backends.rs
index 55ab3ef8..0ba2015d 100644
--- a/src/backends.rs
+++ b/src/backends.rs
@@ -22,7 +22,7 @@ cfg_if! {
     } else if #[cfg(getrandom_backend = "rndr")] {
         mod rndr;
         pub use rndr::*;
-    } else if #[cfg(getrandom_backend = "wasm_js")] {
+    } else if #[cfg(all(feature = "js", getrandom_backend = "wasm_js"))] {
         mod wasm_js;
         pub use wasm_js::*;
     } else if #[cfg(getrandom_backend = "esp_idf")] {
@@ -133,6 +133,18 @@ cfg_if! {
                 );
             }
         }
+    } else if #[cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))] {
+        cfg_if! {
+            if #[cfg(feature = "js")] {
+                mod wasm_js;
+                pub use wasm_js::*;
+            } else {
+                compile_error!("the wasm32-unknown-unknown targets are not supported \
+                                by default, you may need to enable the \"js\" \
+                                feature flag. For more information see: \
+                                https://docs.rs/getrandom/#webassembly-support");
+            }
+        }
     } else if #[cfg(target_os = "hermit")] {
         mod hermit;
         pub use hermit::*;
@@ -151,14 +163,6 @@ cfg_if! {
     } else if #[cfg(all(target_arch = "x86_64", target_env = "sgx"))] {
         mod rdrand;
         pub use rdrand::*;
-    } else if #[cfg(all(
-        target_arch = "wasm32",
-        any(target_os = "unknown", target_os = "none")
-    ))] {
-        compile_error!("the wasm32-unknown-unknown targets are not supported \
-                        by default, you may need to enable the \"wasm_js\" \
-                        configuration flag. For more information see: \
-                        https://docs.rs/getrandom/#webassembly-support");
     } else {
         compile_error!("target is not supported. You may need to define \
                         a custom backend see: \
diff --git a/src/error.rs b/src/error.rs
index 4004af57..aafff56c 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -118,7 +118,7 @@ impl Error {
             Error::WINDOWS_PROCESS_PRNG => "ProcessPrng: Windows system function failure",
             #[cfg(all(windows, target_vendor = "win7"))]
             Error::WINDOWS_RTL_GEN_RANDOM => "RtlGenRandom: Windows system function failure",
-            #[cfg(getrandom_backend = "wasm_js")]
+            #[cfg(all(feature = "js", getrandom_backend = "wasm_js"))]
             Error::WEB_CRYPTO => "Web Crypto API is unavailable",
             #[cfg(target_os = "vxworks")]
             Error::VXWORKS_RAND_SECURE => "randSecure: VxWorks RNG module is not initialized",
diff --git a/tests/mod.rs b/tests/mod.rs
index c972e768..fac1f81d 100644
--- a/tests/mod.rs
+++ b/tests/mod.rs
@@ -2,7 +2,7 @@ use core::mem::MaybeUninit;
 use getrandom::{fill, fill_uninit};
 
 #[cfg(all(
-    getrandom_backend = "wasm_js",
+    feature = "js",
     target_arch = "wasm32",
     target_os = "unknown"
 ))]

From a94fe508659afead9ba65e5b1a2de0c3e038ed1a Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Fri, 3 Jan 2025 08:55:32 +0000
Subject: [PATCH 05/13] CI: use feature js where required

---
 .github/workflows/build.yml     | 6 +++---
 .github/workflows/workspace.yml | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 4a251776..c68487f6 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -140,8 +140,8 @@ jobs:
       fail-fast: false
       matrix:
         target: [
-          { description: Web, target: wasm32-unknown-unknown },
-          { description: WasmV1, target: wasm32v1-none },
+          { description: Web, target: wasm32-unknown-unknown, feature: "--features js" },
+          { description: WasmV1, target: wasm32v1-none, feature: "" },
         ]
         feature: [
           { description: no_std, feature: "", build-std: "core,alloc", std: false },
@@ -163,7 +163,7 @@ jobs:
           components: rust-src
       - uses: Swatinem/rust-cache@v2
       - name: Build
-        run: cargo build --target ${{ matrix.target.target }} ${{ matrix.feature.feature }} -Zbuild-std=${{ matrix.feature.build-std }}
+        run: cargo build --target ${{ matrix.target.target }} ${{ matrix.target.feature }} ${{ matrix.feature.feature }} -Zbuild-std=${{ matrix.feature.build-std }}
 
   rdrand-uefi:
     name: RDRAND UEFI
diff --git a/.github/workflows/workspace.yml b/.github/workflows/workspace.yml
index 7f62034a..b41ec359 100644
--- a/.github/workflows/workspace.yml
+++ b/.github/workflows/workspace.yml
@@ -48,11 +48,11 @@ jobs:
     - name: Web WASM (wasm_js.rs)
       env:
         RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js"
-      run: cargo clippy -Zbuild-std --target wasm32-unknown-unknown
+      run: cargo clippy -Zbuild-std --target wasm32-unknown-unknown --features js
     - name: Web WASM with atomics (wasm_js.rs)
       env:
         RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js" -Ctarget-feature=+atomics,+bulk-memory
-      run: cargo clippy -Zbuild-std --target wasm32-unknown-unknown
+      run: cargo clippy -Zbuild-std --target wasm32-unknown-unknown --features js
     - name: Linux (linux_android.rs)
       env:
         RUSTFLAGS: -Dwarnings --cfg getrandom_backend="linux_getrandom"

From 03b00f138e7756deef34c4edfef9c2e59d8dcc5a Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Fri, 3 Jan 2025 09:05:42 +0000
Subject: [PATCH 06/13] Remove feature rustix

---
 Cargo.toml | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 0e7e8b1c..639c906f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,11 +18,6 @@ std = []
 # Unstable feature to support being a libstd dependency
 rustc-dep-of-std = ["dep:compiler_builtins", "dep:core"]
 
-# Optional backend: linux_rustix
-# This flag enables the backend and uses it by default on Linux/Android.
-# The backend may still be overridden by setting getrandom_backend.
-rustix = ["dep:rustix"]
-
 # Optional backend: wasm_js
 # This flag enables the backend and uses it by default on wasm32 with unknown OS.
 # The backend may still be overridden by setting getrandom_backend.

From 375ba77053b237fe99a6734f3b7bd8d4bf68899a Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Fri, 3 Jan 2025 09:28:14 +0000
Subject: [PATCH 07/13] CI: WasmV1 also needs js

---
 .github/workflows/build.yml | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 6d9e9189..096936f8 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -137,12 +137,12 @@ jobs:
       fail-fast: false
       matrix:
         target: [
-          { description: Web, target: wasm32-unknown-unknown, feature: "--features js" },
-          { description: WasmV1, target: wasm32v1-none, feature: "" },
+          { description: Web, target: wasm32-unknown-unknown },
+          { description: WasmV1, target: wasm32v1-none },
         ]
         feature: [
-          { description: no_std, feature: "", build-std: "core,alloc", std: false },
-          { feature: --features std, build-std: "panic_abort,std", std: true },
+          { description: no_std, feature: "--features js", build-std: "core,alloc", std: false },
+          { feature: --features js,std, build-std: "panic_abort,std", std: true },
         ]
         atomic: [
           { flags: "" },
@@ -160,7 +160,7 @@ jobs:
           components: rust-src
       - uses: Swatinem/rust-cache@v2
       - name: Build
-        run: cargo build --target ${{ matrix.target.target }} ${{ matrix.target.feature }} ${{ matrix.feature.feature }} -Zbuild-std=${{ matrix.feature.build-std }}
+        run: cargo build --target ${{ matrix.target.target }} ${{ matrix.feature.feature }} -Zbuild-std=${{ matrix.feature.build-std }}
 
   rdrand-uefi:
     name: RDRAND UEFI

From 991cbdcfabb89963115c5e1e61c314940a72227d Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Fri, 3 Jan 2025 09:35:21 +0000
Subject: [PATCH 08/13] cargo fmt

---
 tests/mod.rs | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/tests/mod.rs b/tests/mod.rs
index fac1f81d..03247f31 100644
--- a/tests/mod.rs
+++ b/tests/mod.rs
@@ -1,11 +1,7 @@
 use core::mem::MaybeUninit;
 use getrandom::{fill, fill_uninit};
 
-#[cfg(all(
-    feature = "js",
-    target_arch = "wasm32",
-    target_os = "unknown"
-))]
+#[cfg(all(feature = "js", target_arch = "wasm32", target_os = "unknown"))]
 use wasm_bindgen_test::wasm_bindgen_test as test;
 
 #[test]

From eb060c316b011f9af539122b8dda8e5195b6f4bf Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Fri, 3 Jan 2025 09:36:13 +0000
Subject: [PATCH 09/13] CI: remove rustix job

---
 .github/workflows/tests.yml | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index cf1f7dfc..d27fd690 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -56,9 +56,6 @@ jobs:
       - env:
           RUSTFLAGS: -Dwarnings --cfg getrandom_backend="linux_getrandom"
         run: cargo test --target=${{ matrix.target }} --features=std
-      - env:
-          RUSTFLAGS: -Dwarnings --cfg getrandom_backend="linux_rustix"
-        run: cargo test --target=${{ matrix.target }} --features=rustix,std
       - env:
           RUSTFLAGS: -Dwarnings --cfg getrandom_test_linux_fallback
         run: cargo test --features=std

From f3c8a3884224503c1db543deeefa1f54a0af55b3 Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Fri, 3 Jan 2025 09:37:21 +0000
Subject: [PATCH 10/13] CI: formatting fix

---
 .github/workflows/build.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 096936f8..f2e0c480 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -142,7 +142,7 @@ jobs:
         ]
         feature: [
           { description: no_std, feature: "--features js", build-std: "core,alloc", std: false },
-          { feature: --features js,std, build-std: "panic_abort,std", std: true },
+          { feature: "--features js,std", build-std: "panic_abort,std", std: true },
         ]
         atomic: [
           { flags: "" },

From 43ca98e8a9dde6fc84b192407baf05bf1c85d27b Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Fri, 3 Jan 2025 09:42:41 +0000
Subject: [PATCH 11/13] CI fix

---
 .github/workflows/tests.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index d27fd690..c03495bd 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -244,7 +244,7 @@ jobs:
               version: nightly,
               components: rust-src,
               flags: '-Dwarnings --cfg getrandom_backend="wasm_js" -Ctarget-feature=+atomics,+bulk-memory',
-              args: '--features=std -Zbuild-std=panic_abort,std,js',
+              args: '--features=std,js -Zbuild-std=panic_abort,std',
             }
     steps:
       - uses: actions/checkout@v4

From 0bf8b1b28e3c539f5f4e27509e98b5690b8f2d55 Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Wed, 22 Jan 2025 16:05:31 +0000
Subject: [PATCH 12/13] Rename feature js -> wasm_js and remove auto opt-in

---
 .github/workflows/build.yml     |  4 ++--
 .github/workflows/tests.yml     |  4 ++--
 .github/workflows/workspace.yml |  4 ++--
 Cargo.toml                      |  6 +++---
 README.md                       | 26 +++++++++++++-------------
 src/backends.rs                 | 22 +++++++++-------------
 src/error.rs                    |  2 +-
 tests/mod.rs                    |  2 +-
 8 files changed, 33 insertions(+), 37 deletions(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 5c340c33..707ac362 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -142,8 +142,8 @@ jobs:
           { description: WasmV1, target: wasm32v1-none },
         ]
         feature: [
-          { description: no_std, feature: "--features js", build-std: "core,alloc", std: false },
-          { feature: "--features js,std", build-std: "panic_abort,std", std: true },
+          { description: no_std, feature: "--features wasm_js", build-std: "core,alloc", std: false },
+          { feature: "--features wasm_js,std", build-std: "panic_abort,std", std: true },
         ]
         atomic: [
           { flags: "" },
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index c03495bd..57cf9e87 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -237,14 +237,14 @@ jobs:
           - {
               description: Web,
               version: stable,
-              args: '--features=std,js',
+              args: '--features=std,wasm_js',
             }
           - {
               description: Web with Atomics,
               version: nightly,
               components: rust-src,
               flags: '-Dwarnings --cfg getrandom_backend="wasm_js" -Ctarget-feature=+atomics,+bulk-memory',
-              args: '--features=std,js -Zbuild-std=panic_abort,std',
+              args: '--features=std,wasm_js -Zbuild-std=panic_abort,std',
             }
     steps:
       - uses: actions/checkout@v4
diff --git a/.github/workflows/workspace.yml b/.github/workflows/workspace.yml
index 994db90e..14b37dd9 100644
--- a/.github/workflows/workspace.yml
+++ b/.github/workflows/workspace.yml
@@ -48,11 +48,11 @@ jobs:
     - name: Web WASM (wasm_js.rs)
       env:
         RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js"
-      run: cargo clippy -Zbuild-std --target wasm32-unknown-unknown --features js
+      run: cargo clippy -Zbuild-std --target wasm32-unknown-unknown --features wasm_js
     - name: Web WASM with atomics (wasm_js.rs)
       env:
         RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js" -Ctarget-feature=+atomics,+bulk-memory
-      run: cargo clippy -Zbuild-std --target wasm32-unknown-unknown --features js
+      run: cargo clippy -Zbuild-std --target wasm32-unknown-unknown --features wasm_js
     - name: Linux (linux_android.rs)
       env:
         RUSTFLAGS: -Dwarnings --cfg getrandom_backend="linux_getrandom"
diff --git a/Cargo.toml b/Cargo.toml
index 4c795c23..8e6d0e6a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,9 +19,9 @@ std = []
 rustc-dep-of-std = ["dep:compiler_builtins", "dep:core"]
 
 # Optional backend: wasm_js
-# This flag enables the backend and uses it by default on wasm32 with unknown OS.
-# The backend may still be overridden by setting getrandom_backend.
-js = ["dep:wasm-bindgen", "dep:js-sys"]
+# This flag enables the backend but does not select it. To use the backend, use
+# this flag *and* set getrandom_backend=wasm_js (see README).
+wasm_js = ["dep:wasm-bindgen", "dep:js-sys"]
 
 [dependencies]
 cfg-if = "1"
diff --git a/README.md b/README.md
index 6e7e3e28..0007634c 100644
--- a/README.md
+++ b/README.md
@@ -82,7 +82,7 @@ of randomness based on their specific needs:
 | `linux_getrandom` | Linux, Android       | `*‑linux‑*`              | [`getrandom`][1] system call (without `/dev/urandom` fallback). Bumps minimum supported Linux kernel version to 3.17 and Android API level to 23 (Marshmallow).
 | `rdrand`          | x86, x86-64          | `x86_64-*`, `i686-*`     | [`RDRAND`] instruction
 | `rndr`            | AArch64              | `aarch64-*`              | [`RNDR`] register
-| `wasm_js`         | Web Browser, Node.js | `wasm32‑unknown‑unknown`, `wasm32v1-none` | [`Crypto.getRandomValues`]. Requires feature `js`.
+| `wasm_js`         | Web Browser, Node.js | `wasm32‑unknown‑unknown`, `wasm32v1-none` | [`Crypto.getRandomValues`]. Requires feature `wasm_js` ([see below](#webassembly-support)).
 | `custom`          | All targets          | `*`                      | User-provided custom implementation (see [custom backend])
 
 Opt-in backends can be enabled using the `getrandom_backend` configuration flag.
@@ -112,19 +112,19 @@ the `wasm32-unknown-unknown` target (i.e. the target used by `wasm-pack`)
 is not automatically supported since, from the target name alone, we cannot deduce
 which JavaScript interface should be used (or if JavaScript is available at all).
 
-Instead, *if the `js` feature is enabled*, this crate will assume
-that you are building for an environment containing JavaScript, and will
-call the appropriate Web Crypto methods [described above](#opt-in-backends) using
-the [`wasm-bindgen`] toolchain (with or without using `getrandom_backend=wasm_js`).
-Both web browser (main window and Web Workers)
-and Node.js (v19 or later) environments are supported.
+To enable `getrandom`'s functionality on `wasm32-unknown-unknown` using the Web
+Crypto methods [described above](#opt-in-backends) via [`wasm-bindgen`], do
+*both* of the following:
 
-To enable the `wasm_js` backend, you can add the following lines to your
-project's `.cargo/config.toml` file:
-```toml
-[dependencies]
-getrandom = { version = "0.3", features = ["js"] }
-```
+-   Use the `wasm_js` feature flag, i.e.
+    `getrandom = { version = "0.3", features = ["wasm_js"] }`.
+    On its own, this only makes the backend available. (As a side effect this
+    will make your `Cargo.lock` significantly larger if you are not already
+    using [`wasm-bindgen`], but otherwise enabling this feature is harmless.)
+-   Set `RUSTFLAGS='--cfg getrandom_backend="wasm_js"'` ([see above](#opt-in-backends)).
+
+This backend supports both web browsers (main window and Web Workers)
+and Node.js (v19 or later) environments.
 
 ### Custom backend
 
diff --git a/src/backends.rs b/src/backends.rs
index 7abb8d3f..fd360b31 100644
--- a/src/backends.rs
+++ b/src/backends.rs
@@ -19,7 +19,7 @@ cfg_if! {
     } else if #[cfg(getrandom_backend = "rndr")] {
         mod rndr;
         pub use rndr::*;
-    } else if #[cfg(all(feature = "js", getrandom_backend = "wasm_js"))] {
+    } else if #[cfg(all(feature = "wasm_js", getrandom_backend = "wasm_js"))] {
         mod wasm_js;
         pub use wasm_js::*;
     } else if #[cfg(target_os = "espidf")] {
@@ -127,18 +127,6 @@ cfg_if! {
                 );
             }
         }
-    } else if #[cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))] {
-        cfg_if! {
-            if #[cfg(feature = "js")] {
-                mod wasm_js;
-                pub use wasm_js::*;
-            } else {
-                compile_error!("the wasm32-unknown-unknown targets are not supported \
-                                by default, you may need to enable the \"js\" \
-                                feature flag. For more information see: \
-                                https://docs.rs/getrandom/#webassembly-support");
-            }
-        }
     } else if #[cfg(target_os = "hermit")] {
         mod hermit;
         pub use hermit::*;
@@ -157,6 +145,14 @@ cfg_if! {
     } else if #[cfg(all(target_arch = "x86_64", target_env = "sgx"))] {
         mod rdrand;
         pub use rdrand::*;
+    } else if #[cfg(all(
+        target_arch = "wasm32",
+        any(target_os = "unknown", target_os = "none")
+    ))] {
+        compile_error!("the wasm32-unknown-unknown targets are not supported \
+                        by default, you may need to enable the \"wasm_js\" \
+                        configuration flag. For more information see: \
+                        https://docs.rs/getrandom/#webassembly-support");
     } else {
         compile_error!("target is not supported. You may need to define \
                         a custom backend see: \
diff --git a/src/error.rs b/src/error.rs
index d94ca2a4..ccbe7837 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -116,7 +116,7 @@ impl Error {
             Error::IOS_RANDOM_GEN => "SecRandomCopyBytes: iOS Security framework failure",
             #[cfg(all(windows, target_vendor = "win7"))]
             Error::WINDOWS_RTL_GEN_RANDOM => "RtlGenRandom: Windows system function failure",
-            #[cfg(all(feature = "js", getrandom_backend = "wasm_js"))]
+            #[cfg(all(feature = "wasm_js", getrandom_backend = "wasm_js"))]
             Error::WEB_CRYPTO => "Web Crypto API is unavailable",
             #[cfg(target_os = "vxworks")]
             Error::VXWORKS_RAND_SECURE => "randSecure: VxWorks RNG module is not initialized",
diff --git a/tests/mod.rs b/tests/mod.rs
index 03247f31..9f1e6338 100644
--- a/tests/mod.rs
+++ b/tests/mod.rs
@@ -1,7 +1,7 @@
 use core::mem::MaybeUninit;
 use getrandom::{fill, fill_uninit};
 
-#[cfg(all(feature = "js", target_arch = "wasm32", target_os = "unknown"))]
+#[cfg(all(feature = "wasm_js", target_arch = "wasm32", target_os = "unknown"))]
 use wasm_bindgen_test::wasm_bindgen_test as test;
 
 #[test]

From 50b68ba9f8a8343486a7525a75a8a2f56668f442 Mon Sep 17 00:00:00 2001
From: Diggory Hardy <git@dhardy.name>
Date: Wed, 22 Jan 2025 16:57:27 +0000
Subject: [PATCH 13/13] Fix Web test and improve error msgs for wasm_js

---
 .github/workflows/tests.yml |  1 +
 src/backends.rs             | 32 +++++++++++++++++++++-----------
 2 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 57cf9e87..28b91ab9 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -237,6 +237,7 @@ jobs:
           - {
               description: Web,
               version: stable,
+              flags: '-Dwarnings --cfg getrandom_backend="wasm_js"',
               args: '--features=std,wasm_js',
             }
           - {
diff --git a/src/backends.rs b/src/backends.rs
index fd360b31..1509af11 100644
--- a/src/backends.rs
+++ b/src/backends.rs
@@ -19,9 +19,19 @@ cfg_if! {
     } else if #[cfg(getrandom_backend = "rndr")] {
         mod rndr;
         pub use rndr::*;
-    } else if #[cfg(all(feature = "wasm_js", getrandom_backend = "wasm_js"))] {
-        mod wasm_js;
-        pub use wasm_js::*;
+    } else if #[cfg(all(getrandom_backend = "wasm_js"))] {
+        cfg_if! {
+            if #[cfg(feature = "wasm_js")] {
+                mod wasm_js;
+                pub use wasm_js::*;
+            } else {
+                compile_error!(
+                    "The \"wasm_js\" backend requires the `wasm_js` feature \
+                    for `getrandom`. For more information see: \
+                    https://docs.rs/getrandom/#webassembly-support"
+                );
+            }
+        }
     } else if #[cfg(target_os = "espidf")] {
         mod esp_idf;
         pub use esp_idf::*;
@@ -145,14 +155,14 @@ cfg_if! {
     } else if #[cfg(all(target_arch = "x86_64", target_env = "sgx"))] {
         mod rdrand;
         pub use rdrand::*;
-    } else if #[cfg(all(
-        target_arch = "wasm32",
-        any(target_os = "unknown", target_os = "none")
-    ))] {
-        compile_error!("the wasm32-unknown-unknown targets are not supported \
-                        by default, you may need to enable the \"wasm_js\" \
-                        configuration flag. For more information see: \
-                        https://docs.rs/getrandom/#webassembly-support");
+    } else if #[cfg(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "none")))] {
+        compile_error!(
+            "The wasm32-unknown-unknown targets are not supported by default; \
+            you may need to enable the \"wasm_js\" configuration flag. Note \
+            that enabling the `wasm_js` feature flag alone is insufficient. \
+            For more information see: \
+            https://docs.rs/getrandom/#webassembly-support"
+        );
     } else {
         compile_error!("target is not supported. You may need to define \
                         a custom backend see: \