Add signum

README.md

@@ -28,7 +28,7 @@
 
 **Functional tools that couldn’t be simpler.**
 
-We’re proud to present *1-liners* – a dead simple functional utility belt. **[92 one-liner functions][docs]** (and counting). Each hand-crafted with love and attention.
+We’re proud to present *1-liners* – a dead simple functional utility belt. **[93 one-liner functions][docs]** (and counting). Each hand-crafted with love and attention.
 
 [docs]:  ./documentation
 

documentation/README.md

@@ -83,6 +83,7 @@
 - [replace](#replace)
 - [shallowClone](#shallowclone)
 - [shave](#shave)
+- [signum](#signum)
 - [some](#some)
 - [split](#split)
 - [startsWith](#startswith)
@@ -1631,6 +1632,30 @@ map(shave(1, parseInt), [0, 1.1, 2.2]); // => [0, 1, 2]
 </sup></div>
 
 
+### signum
+
+Returns [`1` if `n` is positive, `-1` if `n` is negative and `0` if `n` is `0`]. Otherwise returns `NaN`.
+
+```js
+const signum = require('1-liners/signum');
+
+signum(-5);         // => -1
+signum(-Infinity);  // => -1
+
+signum(10);         // => 1
+signum(Infinity);   // => 1
+
+signum(0);          // => 0
+signum(-0);         // => 0
+```
+
+<div align="right"><sup>
+	<a href="../tests/signum.js">Spec</a>
+	•
+	<a href="../module/signum.js">Source</a>: <code> (n) =&gt; (n === 0 ? 0 : (n &gt; 0 ? 1 : (n &lt; 0 ? -1 : NaN)));</code>
+</sup></div>
+
+
 ### some
 
 Same as `[1,2,3].some(GreaterThan16)`

module/index.js

@@ -76,6 +76,7 @@ import reduceRight from './reduceRight';
 import replace from './replace';
 import shallowClone from './shallowClone';
 import shave from './shave';
+import signum from './signum';
 import some from './some';
 import split from './split';
 import startsWith from './startsWith';
@@ -169,6 +170,7 @@ export {
   replace,
   shallowClone,
   shave,
+  signum,
   some,
   split,
   startsWith,

module/signum.js

@@ -0,0 +1,22 @@
+/**
+ * @module 1-liners/signum
+ *
+ * @description
+ *
+ * Returns [`1` if `n` is positive, `-1` if `n` is negative and `0` if `n` is `0`]. Otherwise returns `NaN`.
+ *
+ * @example
+ *
+ * 	const signum = require('1-liners/signum');
+ *
+ * 	signum(-5);         // => -1
+ * 	signum(-Infinity);  // => -1
+ *
+ * 	signum(10);         // => 1
+ * 	signum(Infinity);   // => 1
+ *
+ * 	signum(0);          // => 0
+ * 	signum(-0);         // => 0
+ *
+ */
+export default (n) => (n === 0 ? 0 : (n > 0 ? 1 : (n < 0 ? -1 : NaN)));

tests/signum.js

@@ -0,0 +1,15 @@
+import { equal, ok } from 'assert';
+import signum from '../signum';
+
+test('#signum', () => {
+	equal(signum(-5),         -1);
+	equal(signum(-Infinity),  -1);
+
+	equal(signum(10),        1);
+	equal(signum(Infinity),  1);
+
+	equal(signum(0),   0);
+	equal(signum(-0),  0);
+
+	ok(Number.isNaN(signum(NaN)));
+});