Arrow functions in ES6

    The arrow function in ES6 simplifies the spelling of the function, the grammar is more readable, and the form is more intuitive. The following describes the arrow writing for single-parameter functions, multi-parameter functions, and non-parameter functions.

1. Single parameter function

    //1) 原版
    var print = function (obj) {
    
    
        console.log(obj)
    }
    print("hello")

	//2) 箭头版
    var print2 = obj => console.log(obj)
    print2("world")

2. Multi-parameter function

    //1) 原版
    var sum = function (a,b) {
    
    
        return a+b
    }
    //2) 箭头版
    var sum2 = (a,b) => a+b
	
	//打印
    console.log("#1:"+sum(2,3))
    console.log("#2:"+sum2(2,3))

3. Function without parameters

    let sayhello = () => console.log("hello")
    
    sayhello()

4. Brackets {} wrap multiple lines

    var sum3 = (a,b) => {
    
    
        return a+b
    }

    let sayHello = () => {
    
    
        console.log("hello!")
        console.log("world!")
    }
    sayHello()