Prototype apply loses my scope

Asked Jul 09 '18 at 15:30

Active Jul 09 '18 at 15:36

Viewed 20 times

I am calling function which return result to callback(this is old library) by using prototype apply. But after this I'am losing my this scope in the callback.

export default {
CONSTANCT: 123,

x () {
    var arr = [1, 2, this.yCallback]
    this.y.apply(this, arr) //trying give null instead this, but now works too
},

y (a, b, callback) {
    var c = a + b

    callback(c)
},

yCallback (result) {
    console.log(result)
    console.log(this.CONSTANCT)
}

}

in yCallback function this - undefined

Changing string callback(c) to callback.apply(this, [c]) resolve the problem. But i really want to avoid library fixes

edited Jul 09 '18 at 15:36

asked Jul 09 '18 at 15:30

ItsMyLife

2

`this.yCallback.bind(this)` – Keith Jul 09 '18 at 15:35
@Li357 apply will call it there and then, bind will bind `this` to the function. – Keith Jul 09 '18 at 15:37
@Keith My bad, I misread. To OP: `this` is lost when you do `callback(c)`. You aren't calling `callback` from an object thus no 'context'. Bind `yCallback`. – Andrew Li Jul 09 '18 at 15:37

Prototype apply loses my scope

0 Answers0