Arrow function - Getting Started (study notes)

Arrow function (Arrow Functions)

A more concise wording

1. The original wording

function method(params){
　　return params*2;
}

2. Functions arrow

(params)  => {params*2;} 

Get a line.

a. If only one parameter, the brackets can be omitted

params  => {params*2;} 

b. If only one expression, braces can be omitted

params => params*2;

Second, this point will not change

Example: Implementing a ++

var Method = function(){
　　this.a = 0;
　　this.timer = setInterval(function(){
　　　　this.a++;
　　　　console.log(this.a);
　　},1000);
}
var method = new Method();

Output:

NaN 
NaN 
NaN 
...

Because setInterval function, this, pointed windows, windows in a defined, you can not output the desired value.

Modify arrow function can be achieved a ++;

var Method = function(){
　　this.a = 0;
　　this.timer = setInterval(() => {
　　　　this.a++;
　　　　console.log(this.a);
　　})
}
var method = new Method();

Output:

1
2
3
...