Why cant I call my function in setInterval() inside a class ?

Question

In the code , calling this.update() works normally but not inside a setTimeout()
Can anyone tell me why and how to fix it .
https://code.sololearn.com/WUi5cd1vF6c2/?ref=app

Answer 1

this is out of scope when use in timer function.
Declare a this var for timer function use.

eg.
var that = this;
setTimeout(function(){
console.log("what")
that.update();
},1000);

Answer 2

do this:

var self = this;
//error this.update() is not a function
setTimeout(function(){
console.log("what")
self.update();
},1000);
//************

this inside the setTimeout function is of a different context (it's not the same this)

we have to save it to a variable before and use it then

Answer 3

damn Calviղ is a quick one ._.

Answer 4

i submit to you oh mighty Calviղ 🙌

Answer 5

you earned it >:D

Answer 6

The timer function run in separate execution using Window object, so the "this" points to Window global object in timer function.

Btw Utkαrsh the program generates nice effect ☺👍🏼

Answer 7

It's my honour to be called mighty by Burey 😁

Answer 8

Thank You Burey and Calviղ , I get it now.
Calvin get the best answer for the speed
:-P

I thought that might be the problem , but I only tried this.this.update() ..lol

What does the "this" point to inside the setTimeout anyway the function itself or something else

Answer 9

The proper solution is:

setTimeout(function(){
console.log("what")
this.update();
}.bind(this) ,1000);

Simply binding the context of ‘this’ to the function. The bind function returns another function, wrapping the initial one and setting ‘this’ to whatever you supply as a parameter of the bind method.

“var that = this” is frowned upon in industry, but unavoidable in some situations - not this one.

Answer 10

Burey 🤣