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copied!<blockquote> <p><em>"The code above neither work with the this keyword nor without it. Why is that?"</em></p> </blockquote> <p>Though you talk about JSON, when reading the text of your question, it sounds like what you're asking is how to use <code>this</code> to refer to the object during its creation when using object literal syntax.</p> <p>The reason <code>this</code> isn't working for you is that its value is defined only within a function, and what defines it is <em>how</em> the function was invoked. </p> <p>Although your code does provide a function, it has no way to refer to the object during creation, because there's no reference available to it until <em>after</em> the literal syntax.</p> <hr> <blockquote> <p><em>"The only working solution is to assign the JSON object to a variable and to use the variable in the code."</em></p> </blockquote> <p>That's right, you can't use <code>this</code> in object literal syntax to refer to the new object, so you'd need to use a variable reference after. </p> <p>Though as an alternative to the literal syntax, you can use a constructor function to create the object. That way you don't need to use the variable to create the <code>fullName</code> property after the object is already created.</p> <pre><code>var obj = new function() { this.firstName = "Foo"; this.lastName = "Bar"; this.fullName = this.firstName + " " + this.lastName; }; </code></pre> <p>This is also useful if you're passing the object to a function.</p> <pre><code>my_func(new function() { this.firstName = "Foo"; this.lastName = "Bar"; this.fullName = this.firstName + " " + this.lastName; }); </code></pre> <hr> <p>So the reason you can use <code>this</code> is that as I stated above, <code>this</code> is defined within a function, and is defined based on how the function was invoked. </p> <p>Here we're using an anonymous function as a constructor by invoking it using <code>new</code>. That makes <code>this</code> refer to a new object being constructed, which is then returned from the constructor function automatically.</p>

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