2.知识剖析

下面是介绍几个ES6的新特性

箭头函数

                    var f = v => v;
                    f();
                    console.log('f()', f());
                    
                    var g = function (v) {
                        return v;
                        console.log('v', v);
                    }
                    g();
                    console.log('g()', g());
                    
                 
            

当你的函数有且仅有一个参数的时候，是可以省略掉括号的。 当你函数返回有且仅有一个表达式的时候可以省略{} 和 return；例如:

                    var h = () => 5;
                    h();
                    console.log('h()', h());
                    
                    var i = function () {
                        return 5;
                    }
                    i();
                    console.log('i()', i());
            

解构赋值

                        let [a,b,c]=[1,[2,3],[4]];
                        console.log(a,b,c);
const people = {
        name: 'lux',
        age: 20
    }
    const name = people.name
    const age = people.age
            

使用ES6

                        var l = [1, 2, 3].map(function (x) {
                            return x * x;
                        })
                        console.log('l', l);
                        let n = [1, 2, 3].map(x => x * x);
                        console.log('n', n);
            

函数参数默认值

function foo(height, color)
{
    var height = height || 50;
    var color = color || 'red';
    //...
}
            

因为0的布尔值为false，这样height的取值将是50。同理color的取值为‘red’。

使用ES6

function foo(height = 50, color = 'red')
{
    // ...
}
            

模板字符串

不使用ES6

var name = 'Your name is ' + first + ' ' + last + '.'
            

使用ES6,将变量放在大括号之中：

var name = `Your name is ${first} ${last}.`
            

多行字符串

var roadPoem = 'Then took the other, as just as fair,\n\t'
    + 'And having perhaps the better claim\n\t'
    + 'Because it was grassy and wanted wear,\n\t'
    + 'Though as for that the passing there\n\t'
    + 'Had worn them really about the same,\n\t'

            

使用ES6

var roadPoem = `Then took the other, as just as fair,
    And having perhaps the better claim
    Because it was grassy and wanted wear,
    Though as for that the passing there
    Had worn them really about the same,`
            

对象属性简写

  function people(name, age) {
        return {
            name: name,
            age: age
        };
    }
            

使用ES6

   function people(name, age) {
        return {
            name,
            age
        };
    }