difference between this.key and this[key] using angularjs forEach

Question

I am looping over a simple object using forEach function, I'm passing the object as the context.

When I try to access an object property using this[key] it works but this.key doesn't work, can someone tell us why it behaves so?

var calendar =  {
        moveAll: false,
        moveSingleDay: false,
        translateRange : false
}

angular.forEach(calendar, function(val, key){
      console.log(this[key]); // returns val
      console.log(this.key); // returns undefined
}, calendar);

Possible duplicate of [Dynamically access object property using variable](http://stackoverflow.com/questions/4244896/dynamically-access-object-property-using-variable) — Rajesh, Jan 05 '16 at 10:05

score 5 · Accepted Answer · answered Jan 05 '16 at 10:01

5

this.key is equivalent to this['key'].

answered Jan 05 '16 at 10:01

freakish

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this['key'] allow you to do ... var str = 'key' ... this[str] ... thus you can dynamically access properties – danday74 Jan 05 '16 at 10:18

Victor Dombrovsky · Answer 2 · 2016-01-05T10:21:11.427

2

That is because your calendar object has no property named key.

Note: In the expression this.key key won't be replaced by the value of variable named key.

edited Jan 05 '16 at 10:21

answered Jan 05 '16 at 10:03

Victor Dombrovsky

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score 0 · Answer 3 · answered Jan 05 '16 at 10:17

0

The key variable will contain the indexes of your array, for example: (1,2,3...) what you are trying to do when you type this.key is like this.1 that why you get undefined

answered Jan 05 '16 at 10:17

Anas Youbi

65
6

difference between this.key and this[key] using angularjs forEach

3 Answers3