copilot is a lifesaver

src/base.ts

@@ -1,6 +1,7 @@
 import type { NumberSystem } from ".";
 import * as util from "./util";
 
+/** Creates a new number system object with the given radix/base. */
 export function base(radix: number): NumberSystem {
     const rdx = Math.floor(Math.min(36, Math.max(2, radix)));
     const max = (255).toString(rdx).length;
@@ -17,7 +18,7 @@ export function base(radix: number): NumberSystem {
             const charMatch = data.toString().toLowerCase().match(this.regex);
             if (charMatch == null) return "";
 
-            const decoded = Buffer.from(util.padStart(charMatch, max).map(x => parseInt(x, rdx)));
+            const decoded = Buffer.from(util.padStart((data.toString().toLowerCase().match(this.regex) ?? []).join(""), max).map(x => parseInt(x, rdx)));
             return encoding ? decoded.toString(encoding) : decoded;
         }
     }

src/base32.ts

@@ -4,10 +4,11 @@ export const charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
 export const radix = 32;
 export const regex = /[A-Z2-7]/gi;
 
-const bits = util.quickMap(5, x => 2 ** (x * 8)).reverse();
-const chars = util.quickMap(8, x => 2 ** (x * 5)).reverse();
-const pads = util.quickMap(5, x => (8 - Math.ceil(x * 8 / 5)) % 8);
+const bits = util.quickMap(5, x => 2 ** (x * 8), true); // 4294967296, 16777216, 65536, 256, 1
+const chars = util.quickMap(8, x => 2 ** (x * 5), true); // 34359738368, 1073741824, 33554432, 1048576, 32768, 1024, 32, 1
+const pads = util.quickMap(5, x => (8 - Math.ceil(x * 8 / 5)) % 8, false); // 0, 6, 4, 3, 1
 
+// Encodes the given data into a Base 32 encoded string.
 export function encode(data: string | Buffer, encoding: BufferEncoding = "utf8") {
     let padding = 0;
     return Buffer.from(data.toString(encoding), encoding).reduce((a, x, i, r) => {
@@ -22,8 +23,9 @@ export function encode(data: string | Buffer, encoding: BufferEncoding = "utf8")
             charset[Math.floor(x / y) % 32]).join("")).join("") + "=".repeat(padding);
 }
 
+// Decodes the given Base 32 encoded string into a buffer, or a string if a character encoding is provided.
 export function decode(data: string, encoding?: BufferEncoding) {
-    const decoded = Buffer.from(util.padEnd(data.toString().toUpperCase().match(regex) ?? [], 8)
+    const decoded = Buffer.from(util.padEnd((data.toString().toUpperCase().match(regex) ?? []).join(""), 8)
         .flatMap(x => {
             const value = util.stringToNumber(x, charset);
             return bits.slice(0, pads.findIndex(y => y == (x.match(/=/g) ?? []).length) || 5)

src/base64.ts

@@ -4,10 +4,11 @@ export const charset = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123
 export const radix = 64;
 export const regex = /[A-Za-z0-9+/]/gi;
 
-const bits = util.quickMap(3, x => 2 ** (x * 8)).reverse();
-const chars = util.quickMap(4, x => 2 ** (x * 6)).reverse();
-const pads = util.quickMap(3, x => (4 - Math.ceil(x * 4 / 3)) % 4);
+const bits = util.quickMap(3, x => 2 ** (x * 8), true); // 65536, 256, 1
+const chars = util.quickMap(4, x => 2 ** (x * 6), true); // 262144, 4096, 64, 1
+const pads = util.quickMap(3, x => (4 - Math.ceil(x * 4 / 3)) % 4, false); // 0, 2, 1
 
+// Encodes the given data into a Base 64 encoded string.
 export function encode(data: string | Buffer, encoding: BufferEncoding = "utf8") {
     let padding = 0;
     return Buffer.from(data.toString(encoding), encoding).reduce((a, x, i, r) => {
@@ -22,8 +23,9 @@ export function encode(data: string | Buffer, encoding: BufferEncoding = "utf8")
             charset[Math.floor(x / y) % 64]).join("")).join("") + "=".repeat(padding);
 }
 
+// Decodes the given Base 64 encoded string into a buffer, or a string if a character encoding is provided.
 export function decode(data: string, encoding?: BufferEncoding) {
-    const decoded = Buffer.from(util.padEnd(data.toString().replaceAll("-", "+").replaceAll("_", "/").match(regex) ?? [], 4)
+    const decoded = Buffer.from(util.padEnd((data.toString().replaceAll("-", "+").replaceAll("_", "/").match(regex) ?? []).join(""), 4)
         .flatMap(x => {
             const value = util.stringToNumber(x, charset);
             return bits.slice(0, pads.findIndex(y => y == (x.match(/=/g) ?? []).length) || 3)

src/cli.ts

@@ -10,9 +10,10 @@ type Options = {
     out: string;
 }
 
+// Get the version from the package.json file
 const { version } = JSON.parse(fs.readFileSync(path.join(__dirname, "..", "package.json"), "utf8"));
+// The main CLI function
 export = function (argv: string[], mode: "encode" | "decode") {
-    if (!["encode", "decode"].includes(mode)) return process.exit(1);
     const isEncode = mode.startsWith("e");
 
     const descStart = `${mode[0].toUpperCase() + mode.slice(1)}s the specified input data ${isEncode ? "with" : "from"}`;
@@ -61,6 +62,7 @@ export = function (argv: string[], mode: "encode" | "decode") {
         .alias("radix")
         .action(actionHandler);
 
+    // Create a command for each base/radix in the dencodeme object
     for (const [command, base] of Object.entries(dencodeme)
         .filter((x): x is [string, NumberSystem] => typeof x[1] !== "function")
         .map((x): [string, number] => [x[0], x[1].radix])) {
@@ -76,5 +78,6 @@ export = function (argv: string[], mode: "encode" | "decode") {
             .action(actionHandler.bind(null, command as Exclude<keyof typeof dencodeme, "base">));
     }
 
+    // Parse the given arguments and run the program
     program.parse(argv, { from: "user" });
 }

src/index.ts

@@ -2,20 +2,33 @@ import { base } from "./base";
 import * as b32 from "./base32";
 import * as b64 from "./base64";
 
+/** The number system object interface. */
 export interface NumberSystem {
+    /** The character set of the number system. */
     readonly charset: string;
+    /** The radix/base of the number system. */
     readonly radix: number;
+    /** The regex used to match characters in the number system. */
     readonly regex: RegExp;
+    /** Encodes the given data into an encoded string. */
     encode(data: string | Buffer, encoding?: BufferEncoding): string;
+    /** Decodes the given encoded string into a buffer, or a string if a character encoding is provided. */
     decode(data: string, encoding?: BufferEncoding): string | Buffer;
 }
 
 export * from "./base";
 
+/** The binary (Base 2) number system object. */
 export const binary = base(2);
+/** The octal (Base 8) number system object. */
 export const octal = base(8);
+/** The decimal (Base 10) number system object. */
 export const decimal = base(10);
+/** The hexadecimal (Base 16) number system object. */
 export const hexadecimal = base(16);
+/** The Base 32 number system object. */
 export const base32: NumberSystem = b32;
+/** The Base 36 number system object. */
 export const base36 = base(36);
+/** The Base 64 number system object. */
 export const base64: NumberSystem = b64;

src/util.ts

@@ -1,3 +1,4 @@
+// Returns a mapper function to split a string into an array of strings of the given length.
 function getMapper(length: number) {
     return (a: string[], x: string, i: number) => {
         if (i % length == 0) a.push(x);
@@ -6,18 +7,22 @@ function getMapper(length: number) {
     }
 }
 
-export function padStart(data: string[], length: number): string[] {
+// Pads the given string with zeros to the left, and splits it into an array of strings of the given length.
+export function padStart(data: string, length: number): string[] {
     return [ ...Array((length - data.length % length) % length).fill("0"), ...data ].reduce(getMapper(length), []);
 }
 
-export function padEnd(data: string[], length: number): string[] {
+// Pads the given string with equals signs to the right, and splits it into an array of strings of the given length.
+export function padEnd(data: string, length: number): string[] {
     return [ ...data, ...Array((length - data.length % length) % length).fill("=") ].reduce(getMapper(length), []);
 }
 
-export function quickMap(length: number, multiplier: (x: number) => number) {
-    return Array(length).fill(0).map((_, x) => multiplier(x));
+// Creates an array of numbers from 0 to length - 1, and multiplies each number by the given multiplier.
+export function quickMap(length: number, multiplier: (x: number) => number, reverse: boolean = false) {
+    return Array(length).fill(0).map((_, x) => multiplier(reverse ? -x + length - 1 : x));
 }
 
+// Converts the given string to a number using the given character set.
 export function stringToNumber(str: string, charset: string) {
     return str.split("").reverse().map(x => charset.indexOf(x)).reduce((a, x, i) => a + (x >= 0 ? x * charset.length ** i : 0), 0);
 }