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copied!<p><em>"Everything is an object"</em>... that's one of the big misconceptions that exist all around the language.</p> <p><strong>Not</strong> <em>everything</em> is an object, there are what we call <em>primitive values</em>, which are string, number, boolean, null, and undefined.</p> <p>That's true, a string is a <strong>primitive value</strong>, but you can access all the methods inherited from <code>String.prototype</code> as if it were an object.</p> <p>The property <a href="http://ecma262-5.com/ELS5_HTML.htm#Section_11.2.1" rel="noreferrer">accessor operators</a> (the dot and the bracket notation), temporarily convert the string value to a String object, for being able to access those methods, e.g.:</p> <pre><code>"ab".charAt(1); // "b" </code></pre> <p>What happens behind the scenes is something like this:</p> <pre><code>new String("ab").charAt(1); // "b", temporal conversion ToObject </code></pre> <p>As with the other primitive values, such as <code>Boolean</code>, and <code>Number</code>, there are <em>object wrappers</em>, which are simply objects that contain the primitive value, as in your example:</p> <pre><code>var strObj = new String(""); strObj.prop = "foo"; typeof strObj; // "object" typeof strObj.prop; // "string" </code></pre> <p>While with a primitive:</p> <pre><code>var strValue = ""; strValue.prop = "foo"; typeof strValue; // "string" typeof strValue.prop; // "undefined" </code></pre> <p>And this happens because again, the property accessor on the second line above, creates a new temporal object, as:</p> <pre><code>var strValue = ""; new String(strValue).prop = "foo"; // a new object which is discarded //... </code></pre>

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