ES6 from getting started to mastering 05: extended operators and arrow functions of functions

explain

ES6 From entry to Mastery Series （ whole 23 speak ） Learning notes .

Extension operator

• Remainder operator ： Combine multiple independent parameters into an array
• Extension operator ： Split an array , And pass each item as a separate parameter to the function

es5 utilize apply Maximize the array

const arr = [1,2,3,4,66,8,9];
const maxNum = Math.max.apply(null, arr);
console.log(maxNum);

es6 Use the expansion operator to maximize the array

const arr = [1,2,3,4,66,8,9];
const maxNum = Math.max(...arr);
console.log(maxNum);

Arrow function

Use => To define ,function(){} be equal to () => {}

let add = function (a, b) {
    
	return a + b;
}
let add2 = (a, b) => {
    
	return a + b;
}
let add3 = (a, b) => a + b;
console.log(add(1, 2));
console.log(add2(1, 2));
console.log(add3(1, 2));

Returns the object ：

let getObj = (val) => {
    
	return {
    
		name: "kaimo",
		value: val
	};
}
let getObj2 = (val) => ({
    name: "kaimo", value: val});
console.log(getObj(313));
console.log(getObj2(666));

Closure function ：

let fn = (function() {
    
	return function() {
    
		console.log("hello es6");
	}
})();
let fn2 = (() => {
    
	return () => {
    
		console.log("hello es6 2");
	}
})();
console.log(fn());
console.log(fn2());