Differences between ways to pass function as parameter in Angular Typescript

Question

What is the difference between these two lines of code (except the fact that second line has an inline function calling "setThing"). I noticed that on the first case Angular change detection didn't run.

someObservable<Thing>.subscribe<Thing>(this.setThing) // change detection didn't run
someObservable<Thing>.subscribe<Thing>(thing => this.setThing(thing)); // change detection worked

setThing(thing :Thing) {
    this.thing = thing;
}

Possible duplicate of How does the "this" keyword work?

toskv
– toskv

2017-03-06 15:29:52 +00:00
Commented Mar 6, 2017 at 15:29 — toskv
– toskv, Commented Mar 6, 2017 at 15:29

eko · Accepted Answer · 2017-03-06 11:41:55Z

3

Assuming you are using this inside the function. In the first one you lose the lexical this, in the second you don't.

Example:

First one:

setThing(thing :Thing) {
    this.myTemplateThing = thing; // Since your this is not refering to the component you won't be seeing a change
}

answered Mar 6, 2017 at 11:41

eko

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