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copied!<p>@ doesn't do anything in ECMA262. The document uses it as a placeholder for different operators that use the same syntax. For example, they describe compound assignment such as <code>foo @= bar</code> instead of indicating all of the compound assignment operators.</p> <p>Compound assignment operators are those such as <code>x += 1</code>, except there are quite a few of them, thus, use of the @ sign to represent all of them symbolically in the manual only, nothing in code.</p> <p>As Eli Grey points out, this is a feature that exists in <em><a href="https://secure.wikimedia.org/wikipedia/en/wiki/E4X" rel="nofollow">EcmaScript for XML</a></em>, often nicnamed <em>E4X</em>, offically named ECMA-357.</p> <p>It's important to note that E4X support is presently not common everywhere, and not really the most suitable standard "for the open web", as the WikiPedia article states:</p> <blockquote> <p>E4X <strong>is supported</strong> by Mozilla's <strong>Rhino</strong>, used in <strong>OpenOffice</strong>.org and several other projects, and <strong>SpiderMonkey, used in Firefox, Thunderbird, and other XUL-based applications.</strong> It is also supported by Tamarin, the JavaScript engine used in the Flash virtual machine. It is <strong>not supported</strong> by Nitro (<strong>Safari</strong>), V8 (Google <strong>Chrome</strong>), <strong>Opera</strong>, nor <strong>Internet Explorer</strong>.<a href="https://secure.wikimedia.org/wikipedia/en/wiki/E4X" rel="nofollow">1</a></p> </blockquote> <p>From the E4X example on the page, </p> <p>You can assign a variable some XML data (in much the same way we can use JSON syntax to assign objects)</p> <pre><code>var sales = <sales vendor="John"> <item type="peas" price="4" quantity="6"/> <item type="carrot" price="3" quantity="10"/> <item type="chips" price="5" quantity="3"/> </sales>; </code></pre> <p>Then, to get an attribute value, such as the value of "vendor", we can do</p> <pre><code>alert( sales.@vendor ); </code></pre> <p>And get back "John" in the alert box.</p>

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