箭头函数的使用

1.省略了function的书写，让代码更加简洁

            let say_hello=function(){
 				console.log('hello world!');
			}
			let delete_function=()=>{
				console.log('I had deleted function!');
			}
			say_hello();
			delete_function();

输出：

hello world!

I had deleted function!

2.不能使用伪数组

            let input = function() {
				for (var k of arguments) {
					console.log(k);
				}
			}
			input(1, 2, 3);
           console.log('.........................');
			var hello=()=>{
				for(var k of arguments){
					console.log(k);
				}	
			}
			hello(5,6,7);

输出：

1,2,3

.........................

arguments is not defined

3.不能作为构造实例化对象

            var person = (name, age) => {
				this.name = name,
					this.age = age;
			}
			 let xinyi = new person('xie', 'wang');
			 console.log(xinyi);

输出：

person is not a constructor  //备注(person不是一个构造器)

4.当传入实参只有一个时候，可以省略小括号
 

			let fruits = asia => {
				console.log(asia);
			}
			fruits('apples');

输出：

apples

5.当花括号内的代码只有一条时并且返回结果时，可以省略大括号
 

            let add = (num1, num2) => num1 + num2;
			console.log(add(2, 5)); 
            console.log('.........................');
            let pow = (num1) => num1 * num1;
			console.log(pow(8));
			

输出：

7

.........................

64

6.静态指向，不能使用call，bind，apply强行改变this指向

            function fun() {
				console.log(this.name);
			}
			var hel = () => {
				console.log(this.name);
			}
			var name = 'strongest强'
			let newname = {
				name: '强哥'
			}
			fun(); 
            console.log('.........................');
			hel();
            console.log('.........................');
			fun.call(newname); 
            console.log('.........................');
			hel.call(newname); 
            console.log('.........................');
            hel.apply(newname);
            console.log('.........................');
            hel.bind(newname)(null);

输出：

strongest强

.........................

strongest强

.........................

强哥

.........................

strongest强

.........................

strongest强

.........................

strongest强