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    <p>Modified from an answer by dbaseman: <a href="https://stackoverflow.com/a/10456344/711085">https://stackoverflow.com/a/10456344/711085</a></p> <pre><code>Object.defineProperty(Array.prototype, 'chunk_inefficient', { value: function(chunkSize) { var array=this; return [].concat.apply([], array.map(function(elem,i) { return i%chunkSize ? [] : [array.slice(i,i+chunkSize)]; }) ); } }); </code></pre> <p>Demo:</p> <pre><code>&gt; [1,2,3,4,5,6,7].chunk_inefficient(3) [[1,2,3],[4,5,6],[7]] </code></pre> <hr> <p><em>minor addendum</em>:</p> <p>I should point out that the above is a not-that-elegant (in my mind) workaround to use <code>Array.map</code>. It basically does the following, where ~ is concatenation:</p> <pre><code>[[1,2,3]]~[]~[]~[] ~ [[4,5,6]]~[]~[]~[] ~ [[7]] </code></pre> <p>It has the same asymptotic running time as the method below, but perhaps a worse constant factor due to building empty lists. One could rewrite this as follows (mostly the same as Blazemonger's method, which is why I did not originally submit this answer):</p> <p>More efficient method:</p> <pre><code>Object.defineProperty(Array.prototype, 'chunk', { value: function(chunkSize) { var R = []; for (var i=0; i&lt;this.length; i+=chunkSize) R.push(this.slice(i,i+chunkSize)); return R; } }); // refresh page if experimenting and you already defined Array.prototype.chunk </code></pre> <hr> <p>My preferred way nowadays is the above, or one of the following:</p> <pre><code>Array.range = function(n) { // Array.range(5) --&gt; [0,1,2,3,4] return Array.apply(null,Array(n)).map((x,i) =&gt; i) }; Object.defineProperty(Array.prototype, 'chunk', { value: function(n) { // ACTUAL CODE FOR CHUNKING ARRAY: return Array.range(Math.ceil(this.length/n)).map((x,i) =&gt; this.slice(i*n,i*n+n)); } }); </code></pre> <p>Demo:</p> <pre><code>&gt; JSON.stringify( Array.range(10).chunk(3) ); [[1,2,3],[4,5,6],[7,8,9],[10]] </code></pre> <p>Or if you don't want an Array.range function, it's actually just a one-liner (excluding the fluff):</p> <pre><code>var ceil = Math.ceil; Object.defineProperty(Array.prototype, 'chunk', {value: function(n) { return Array(ceil(this.length/n)).fill().map((_,i) =&gt; this.slice(i*n,i*n+n)); }}); </code></pre> <p>or</p> <pre><code>Object.defineProperty(Array.prototype, 'chunk', {value: function(n) { return Array.from(Array(ceil(this.length/n)), (_,i)=&gt;this.slice(i*n,i*n+n)); }}); </code></pre>
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    1. COEh, I'd avoid messing with the prototype as the feeling of coolness you get from calling the `chunk` function on the array doesn't really outweigh the extra complexity you're adding and the subtle bugs that messing with built-in prototypes can cause.
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      1. USGordon Gustafson
    2. COHe's not messing with them he's extending them for Arrays. I understand never touching Object.prototype because that would bubble to all objects (everything) but for this Array specific function I don't see any issues.
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    3. COPretty sure that should be `array.map(function(i)` not `array.map(function(elem,i)` though
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      1. USNigel Angel
 

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