[рони]

Shellait,

<script>
var jsScript = 'var text = "hello world"; alert(text);';

function fn(str, num) {
    var reg = /\w+|".*?"|'.*?'/g,
        arr = str.match(reg);
    if (arr) {
        arr = arr.reduce(function(a, b, i) {
            if (!/"/.test(b)) a.push(i);
            return a
        }, []);
        for (; arr.length > num;) arr.splice(Math.random() * arr.length | 0, 1);
        num = 0;
        str = str.replace(reg, function(a) {
            return arr.indexOf(num++) > -1 ? "" : a
        })
    }
    return str
};
for (var i=0; i<5; i++)  {document.write(fn(jsScript, 2)+"<br>")}

</script>