JS_17 ES5,ES6

ES5

Strict Mode

1. Definition method use strict
2. characteristic:
   1. We must define the variables using var
   2. There is scope eval
   3. Prohibition custom function in this point window
   4. Object attributes can not have duplicate names

JSON object

• json.stringify (obj / arr): js target object into json
• json.parse (str): json object into the object js

Object expand

Object.create(prototype,[descriptors])

• Role: create a new object with the specified object as the prototype
• descriptors parameters
  • value: specified value
  • writeable: Can Modify
  • configurable: Can Delete
  • enumerable: if you can use for in traversal

var test1 = {
    name : "test1",
}

var test2 = {}

test2 = Object.create(test1,{
    sex:{
        value : "boy",
        writable : true,
        configurable : true,
        enumerable : true,
    },
    age : {
        value : 18,
    }

})

Arrey expand

• indexOf (): get the first index value in the array
• lastIndexOf (): acquire a value of the last index in the array
• forEach (): iterate
• map (): returns the array after processing
• filter (): Filter Array

var arr = [1,2,3,,2,3,4,5,3,4,5,67,7,8,0]
var index_of = arr.indexOf(3)
console.log(index_of) // 2
var lastindex_of = arr.lastIndexOf(3)
console.log(lastindex_of)
// 无法使用break跳出遍历
arr.forEach(function(v){
    console.log(v)
})
var arr2 = arr.map(function(v){
   return  v + 1
})

console.log(arr2)

var arr3 = arr.filter(function(v){
    return v>2
})
console.log(arr3)

Call,apply,bind

• call (): argument transmitted directly
• apply (): pass parameters in the form of an array
• bind (): direct transmission parameters, is not called immediately return function

var fun = function(a,b){
    console.log(this)
    console.log(a+b)
}

var fun1 = function(){
    var fun1_name = "fun1"
}

fun.call(fun1,"aa","bb")
fun.apply(fun1,["aa","bb"])
// 不会立即调用
var fun3 = fun.bind(fun1,"aa","bb")
fun3()