How to handle lack of JavaScript Object.bind() met

Question

I am writing a bit of JavaScript that uses the Object.bind method.

funcabc = function(x, y, z){ 
    this.myx = x;
    this.playUB = function(w) {
        if ( this.myx === null ) {
            // do blah blah
            return;
        }

        // do other stuff
    };
    this.play = this.playUB.bind(this);
};

Since I develop in WinXP with Firefox and sometimes test in Win7 with IE 9 or 10, I did not notice or pay attention to the fact that IE8 and below do not support bind.

This particular script does not use the canvas, so I'm a little hesitant to write off all IE 8 users.

Is there a standard work-around?

I'm getting around sort of okay in JavaScript, but I'm still a bit of a noob. So forgive me if the solution is totally obvious.

Answer 1

There is a good compatability script on this page: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/bind

Just copy and paste it into your script.

EDIT: placing the script below for clarity.

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;
  };
}

Answer 2

The best solution could be to install Modernizr.

Modernizr tells you whether the current browser has this feature natively implemented or not and it provides a script loader so you can pull in polyfills to backfill functionality in old browsers.

Here is the link to generate your modernizr custom version:
http://modernizr.com/download/#-teststyles-testprop-testallprops-hasevent-prefixes-domprefixes

Answer 3

Function.prototype.bind isn’t supported in Internet Explorer 8 and below. Compatibility chart here: http://kangax.github.io/es5-compat-table/

Mozilla Developer Network provide this alternative for older browsers that don't implemented .bind() natively:

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;
  };
}

Answer 4

The Function constructor is the old-fashioned way of doing this:

var foo = function(x,y,z){ return Function("x,y,z","return Math.max.call(this, x, y, z)")(x,y,z) }
 
var bar = function(x,y,z){ return Function("x,y,z","return Math.min.call(this, x, y, z)")(x,y,z) }
 
console.log(foo(1,2,3) );
 
console.log(bar(3,2,1) );

References

• Functional JavaScript: Harnessing the power of the Function Object
• eval() isn’t evil, just misunderstood
• [Scope] of Functions Created via the Function constructor
• John Resig - Fast JavaScript Max/Min