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

2 Answers 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?');

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?';