[javascript] Function in JavaScript that can be called only once

Here is an example JSFiddle - http://jsfiddle.net/6yL6t/

And the code:

function hashCode(str) {
    var hash = 0, i, chr, len;
    if (str.length == 0) return hash;
    for (i = 0, len = str.length; i < len; i++) {
        chr   = str.charCodeAt(i);
        hash  = ((hash << 5) - hash) + chr;
        hash |= 0; // Convert to 32bit integer
    }
    return hash;
}

var onceHashes = {};

function once(func) {
    var unique = hashCode(func.toString().match(/function[^{]+\{([\s\S]*)\}$/)[1]);

    if (!onceHashes[unique]) {
        onceHashes[unique] = true;
        func();
    }
}

You could do:

for (var i=0; i<10; i++) {
    once(function() {
        alert(i);
    });
}

And it will run only once :)

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