[Vlasenko Fedor]

Эт забыл про worker

function getWorker() {
        var blob;
        window.URL = window.URL || window.webkitURL || window.mozURL || window.msURL;
        var mimeString = 'application/javascript';
        var code = "onmessage = function(e) { postMessage('My' + e.data); }";
        try {
            blob = new Blob([code], {type: mimeString});
        } catch (e) {
            var BlobBuilder = window.BlobBuilder || window.WebKitBlobBuilder ||
                window.MozBlobBuilder || window.MSBlobBuilder;
            var bb = new BlobBuilder();
            bb.append(code);
            blob = bb.getBlob(mimeString);
        }
        var url = window.URL.createObjectURL(blob);
        var worker = new Worker(url);
        URL.revokeObjectURL(url);
        return worker;
    }

    var worker = getWorker();
    worker.postMessage('Test');
    worker.onmessage = function (e) {
        alert(e.data);
    };

Пример Function

var fn = "function (a, b) {\
return a + b;\
}";
var call = Function('return ' + fn)();

alert(call(1, 2));