Pass arguments to anonymous functions using ()() in JavaScript

Question

I'm trying to add a hook to each of the functions in the object, follows are my code and it's runs good.

    function foo(){}
    foo.beforeMethodHook = function(){console.log('Hook was called.');}
    foo.getInstance = function(){
        var newInstance = new foo;
        var funcNames = Object.getOwnPropertyNames(foo);
        for(i in funcNames){
            var funcName = funcNames[i];
            if(funcName == 'getInstance' || funcName == 'beforeMethodHook' || Object.hasOwnProperty(funcName)) continue;
            newInstance[funcName] = function (){
                foo.beforeMethodHook();
                return foo[this].apply(foo,arguments);
            }.bind(funcName);
        }
        return newInstance;
    }
    foo.test1 = function(arg1){console.log('test1 was called. arg1 = ' + arg1);return true;}
    foo.test2 = function(arg1,arg2){console.log('test2 was called. arg1 = ' + arg1 + ' , arg2 = ' + arg2);return true;}
    //Test
    var f = foo.getInstance();
    f.test1('ahaha');
    f.test2('heihei','houhou');

As IE10- don't support function(){}.bind(), I tried to change the .bind() to (function(){})() which follows

    newInstance[funcName] = (function (){
        foo.beforeMethodHook();console.log(arguments);
        return foo[funcName].apply(foo,arguments);
    })(funcName);

But the problem comes, I lose arguments that f.test1('ahaha') has passed. the arguments array only gives ["test1"] which is the function name.

How can I fix that? Thanks in advance.

See http://stackoverflow.com/questions/3120017/javascript-forwarding-function-calls-that-take-variable-number-of-arguments — Kos, Oct 30 '13 at 10:28

score 1 · Accepted Answer · answered Oct 30 '13 at 10:33

You can implement your own bind. Easy version:

if (!Function.prototype.bind) {
    Function.prototype.bind = function(that) {
        var fn = this;
        return function() {
            fn.apply(that, arguments);
        }
    };
}

or proper version:

if (!Function.prototype.bind) {
  Function.prototype.bind = function (oThis) {
    if (typeof this !== "function") {
      // closest thing possible to the ECMAScript 5 internal IsCallable function
      throw new TypeError("Function.prototype.bind - what is trying to be bound is not callable");
    }

    var aArgs = Array.prototype.slice.call(arguments, 1), 
        fToBind = this, 
        fNOP = function () {},
        fBound = function () {
          return fToBind.apply(this instanceof fNOP && oThis
                                 ? this
                                 : oThis,
                               aArgs.concat(Array.prototype.slice.call(arguments)));
        };

    fNOP.prototype = this.prototype;
    fBound.prototype = new fNOP();

    return fBound;
  };
}

Code taken from:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind

score 1 · Answer 2 · answered Oct 30 '13 at 10:33

1

try using the alternative code for bind given over here

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind?redirectlocale=en-US&redirectslug=JavaScript%2FReference%2FGlobal_Objects%2FFunction%2Fbind

answered Oct 30 '13 at 10:33

Aditya Vikas Devarapalli

3,186
2
36
54

score 0 · Answer 3 · answered Oct 30 '13 at 10:34

0

you should do something like this

 newInstance[funcName] = (function (){
        console.log(arguments);
        return function(){
          foo.beforeMethodHook();
          foo[funcName].apply(foo,arguments);
        }
    })(funcName);

answered Oct 30 '13 at 10:34

Grigory

1

Not work. All the method will be override by the last method ever defined, which is "test2" in this case. "test1" no longer exist.. – lol.Wen Oct 31 '13 at 02:37

Pass arguments to anonymous functions using ()() in JavaScript

3 Answers3