How to use the three-dot operator

Let’s first look at an example of using the three-dot operator under the es6 specification:

let fun=function(a,...list){
    console.log(a,list);
};
fun('0','a','b','c');//0 [a,b,c]

As you can see from the above, we can now dynamically set the parameters of the parameters when defining the function object. Count: the first parameter a is an ordinary parameter (ignored),

You can see that there are three dots "..." in front of the second parameter list. There are two of this writing method in the es6 specification. Purpose

1. Used as a parameter.

2 . Used as a spread operator.

● Three points--as parameters:

let fun1='a','b','c');fun1(1,2);=1,2,3);fun2(1);=[x,...y]=[1,2,3=[1,2,3];

● Three points--as extended operations Symbols used:

let arr=[1,2,3=[2,31,...a,4);=document.querySelectorAll('p'console.log(...ps);= Set([1,2,3,3= Map([[1,'a'],[2,'b'],[3,'c'[...map.values];'wbiokr'];='abc''aaa',...str,'ccc'];

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