Javascript prototyping forEach on Object

Question

I want to create a prototype of forEach on objects and here is my code

Object.prototype.forEach = function(el,index){
    for(var k in Object){
        el = Object[k];
        index = k;
    }
}

Then i created an object to test this

var obj = {x:0,y:0,z:1290}
obj.forEach( function(el, index) {
    console.log(el+" "+index);
    alert();
});

This code returns no errors,but neither does it alert or log into console anything. I checked obj object and it does have forEach in it's _proto_ property.I also tried

Object.prototype.forEach = function(el,index){
    for(var k in this){
        el = this[k];
        index = k;
    }
}

It's a reeeeeeeeeeeeeally bad idea to change the prototype of built-in objects. — zerkms, Nov 19 '17 at 06:21
If you want to iterate over the object properties - use `Object.entries()` or `Object.values()`. — zerkms, Nov 19 '17 at 06:23

Allen Luce · Accepted Answer · 2017-11-19T06:23:14.587

1

You actually want your function to take a function and then call that function with each element and index:

Object.prototype.forEach = function(f) {
    for (var k in this) {
        el = this[k];
        index = k;
        f(el, index);
    }
}

edited Nov 19 '17 at 06:23

answered Nov 19 '17 at 06:19

Allen Luce

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score 0 · Answer 2 · answered Nov 19 '17 at 06:25

So Your forEach function of the object is wrong, your forEach function should take a function, you can refer to the forEach of the arrays.

Object.prototype.forEach = function(operation){
    for(var k in this){
        operation(this[k],k,this)
    }
}

var obj = {x:0,y:0,z:1290}

obj.forEach(function(el, index) {
     console.log(el+" "+index);
});

Javascript prototyping forEach on Object

2 Answers2