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    <p>This is to do with the weird way <code>this</code> binding works in JavaScript.</p> <pre><code>[].reverse </code></pre> <p>is the method <code>reverse</code> on an empty list. If you call it, through one of:</p> <pre><code>[].reverse(); []['reverse'](); ([].reverse)(); </code></pre> <p>then it executes with <code>this</code> bound to the list instance <code>[]</code>. But if you detach it:</p> <pre><code>x= [].reverse; x(); </code></pre> <p>it executes with no <code>this</code>-binding, so <code>this</code> in the function points to the global (<code>window</code>) object, in one of JavaScript's worst, most misleading design mistakes.</p> <pre><code>(x=[].reverse)() </code></pre> <p>Is also doing the detach. The assignment operator returns the same function object it was passed so it looks like it's doing nothing, but it has the side-effect of breaking the limited special case that causes JavaScript to bind <code>this</code>.</p> <p>So you are saying:</p> <pre><code>Array.prototype.reverse.call(window) </code></pre> <p><code>reverse</code>, like many other <code>Array.prototype</code> methods, is defined by ECMAScript to work on any native sequence-like object. It reverses the items with number-string keys (up to <code>object.length</code>) and returns the object. So it'll return the object that was passed in for any type that has a <code>length</code> property.</p> <p><code>window</code> has a length property, which corresponds to <code>window.frames.length</code>, so calling this method with <code>this</code> pointing at <code>window</code> will work and return the <code>window</code>. In theory it may still fail, because:</p> <ol> <li><code>window</code> is allowed to be a “host object” rather than a “native object”; in this case the guarantees about what you can pass to other prototypes' methods don't necessarily apply; and</li> <li>if the window actually has frames/iframes, it would try to reverse their order, which wouldn't work because the frame collection is read-only.</li> </ol> <p>However, in current browsers the former case does work and the latter fails silently without an error, so you still get the <code>===window</code> behaviour and not an Exception.</p>
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    1. POCan somebody explain this Javascript method?
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    1. POCan somebody explain this Javascript method?
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    1. CODo you happen to know why it is that somebody would code that up? I mean, I understand why the effect happens of course, but why would I put that in my code? What does it achieve?
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    2. COAbsolutely nothing. It's just showing off one of JavaScript's many unexpected behaviours. If I found this in real code I'd worry!
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    3. COA possible reason to do this might be to check if some other script messed with the window object (`window = open('http://google.com/')` is enough). `var window = (x=[].reverse)();` could restore it locally.
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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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