var fn=function(a){
retrun a;
}
function fn2(a){
retrun a;
}
console.log(fn2(1))
console.log(fn1(1))
箭头:
let fn3=v=>0;
let fn4=()=>{
1:alert(1+2);//不传参;
2:return fn4//把函数打印出来;
}
var obj={
//jineng:()=>this//{retrun this} 一样;
//jineng:function (){
retrun this
}//箭头函数外面指向谁就指向谁;
有function.
}
console.log(fn3(1).像函数表达式;
this指向不变.不能作为构造函数;
不能使用new
返回对象的话.外部用括号;
var fn7=()=>{{
"name":"asdfnasd",
"age":"12"
}
}
var fn8=(b,c="2")=>{
//if()
console.log(b+":"+c)
}
fn8(1)//第二参有默认值;
@;
var fn8=(b,c,d)=>{
//if()
console.log(d)
}
fn8(1,2,4,5,6,7)//第二参有默认值;
2:
var fn8=(b,c,...d)=>{
//if()
console.log(d)
}
fn8(1,2,4,5,6,7)//第二参有默认值;//4,5,6,7
3:数值的扩展:
var arr=[1,2,3]
var arr1=[0,...arr,4]
colsole;//0,1,2,3,4
4;对象的扩展:
1:var age="aadf"
var obj={
name:"liming",
[age]:"12"
}
obj.[age]//12
obj."aadf"//12;
使age 当做变量;
2;
1:var age="aadf"
let name="adsf"
var obj={
//1:age:age
age,
name,
sex,
jineng:function(){
console.log("jineng");
},
jitou:()=>{
console.log("jitou");
},
ji(){
console.log("ji")//常用
}
}
console.log(obj.age)
console.log(obj.name)
console.log(obj.sex)
obj.ji();
obj.jitou();
obj.jineng();
5:对象合并
object.assign()对象合并;