What is this language construct in JS? : <p>Could you please help me to understand what is this in Javascript? What is <strong>a</strong>, what is <strong>a['b']</strong>? How to access the declared content of a construct in the iframe and in the parent window? </p>

<pre><code>var a = window['parent'];
if(a) {
    if(a['b']){
        a['b']({
            "c": 1,
            "d": {
                "e": "f",
                "g": false,
                "h": 1
            },
            "i": 0,
            "j": true
        });
    }
}
</code></pre>

<p>If it is possible give me please a link where I can read about this construction. </p>

<p>Thanks a lot.</p>
