function Contador () {
this.num = 0;
var obj = this;
this.timer = setInterval (function add () {
obj.num++;
console.log (obj.num);
}, 1000);
}
var b = new Contador();
I can not understand right how to use these functions, in this code I did, is there any way to reference this to Counter without assigning to a variable?
If anyone knows of a good place to learn more about using this and these functions, I'm grateful!
... is there any way to reference this to the Counter without assigning to a variable?
Yes, using an Arrow Function instead of a normal function. If you read in the documentation you will see that the Arrow Function does not change this :
An arrow function does not have its own this; the value of the enclosing execution context is used
Translating
An arrow function does not have
thisitself; the% used% is that of the context in which it is found.
Here's how:
function Contador () {
this.num = 0;
this.timer = setInterval (() => { //arrow function aqui
this.num++; //this aqui refere Contador
console.log (this.num); //e aqui também
}, 1000);
}
var b = new Contador(); There are cases where this behavior becomes a disadvantage, when it is necessary for the function to have its own this . In your case it facilitates.
As for this , bind , and call , the question indicated already enough detail:
The Contador() function was assigned to the b object, use within setTimeout the b object that represents this function. The effect will be the same as this of the scope of the Contador() function:
function Contador () {
this.num = 0;
this.timer = setInterval (function add () {
b.num++;
console.log (b.num);
}, 1000);
}
var b = new Contador();A good article about this you can see this link .