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I'm trying to figure out the answer to this question:

Without using Javascript's bind function, implement the magic function so that:

var add = function(a, b) { return a + b; }
var addTo = add.magic(2);

var say = function(something) { return something; }
var wele = say.magic('Hi, how are you?');

addTo(5) == 7;
wele() == 'Hi, how are you?';

I think I need to use call or apply but I just don't know, if someone could point me in the right direction or provide some literature it would be much appreciated.

I'm trying to figure out the answer to this question:

Without using Javascript's bind function, implement the magic function so that:

var add = function(a, b) { return a + b; }
var addTo = add.magic(2);

var say = function(something) { return something; }
var wele = say.magic('Hi, how are you?');

addTo(5) == 7;
wele() == 'Hi, how are you?';

I think I need to use call or apply but I just don't know, if someone could point me in the right direction or provide some literature it would be much appreciated.

• javascript
• node.js

Share Improve this question Follow edited Jan 25, 2016 at 14:08 Jeroen 64k4747 gold badges228228 silver badges366366 bronze badges asked Jan 25, 2016 at 14:00 user2755996user2755996 11511 gold badge33 silver badges88 bronze badges

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2 Answers 2

Sorted by: Reset to default 2

You can use closure, and apply function

Function.prototype.magic = function(){
  var self = this;
  var args = Array.from(arguments);
  
  return function(){
    return self.apply(null, args.concat(Array.from(arguments)));
  }
}


var add = function(a, b) { return a + b; }
var addTo = add.magic(2);

var say = function(something) { return something; }
var wele = say.magic('Hi, how are you?');

console.log(addTo(5) == 7);
console.log(wele() == 'Hi, how are you?');

---

Also you can look to Polyfill for bind function on MDN

Please see below code:

    Object.prototype.magic = function (message) {
        alert(message);
    }
    var add = function (a, b) { return a + b; }
    var addTo = add.magic(2);

    var say = function (something) { return something; }
    var wele = say.magic('Hi, how are you?');

    addTo(5) == 7;
    wele() == 'Hi, how are you?';

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