es5 api

ES5

• Object.create(prototype, descriptors)

    //创建对象
    var o1 = {foo:'bar'};
    var o2 = new Object();
    //Object.create(proto,[descriptors]);
    var o3 = Object.create(null);
    function Person(name) {
    	this.name = name;
    }
    var p1 = new Person('sindy');
    var p2 = Object.create(Person.prototype, {
    	age: {
    		value: 18,
    		writable: false,
    		enumerable: false,
    		configurable: true,
    		//value , writable 和 getter setter函数不能同时设置
    		/*get: function () {
    			if (typeof age === 'undefined') {
    				return 'not set age value yet';
    			} else {
    				return 'your age:' + age;
    			}
    		},
    		set: function (a) {
    			age = a;
    			if (this.cTime == 0) {
    				console.log('set age OK');
    				this.cTime++;
    			} else {
    				console.log('change age OK');
    			}
    		}
    	},*/
    	cTime: {
    		value: 0,
    		writable: true
    	}
    });
  

• Object.defineProperty(object, propertyName, descriptor)

    var p1 = new Person('alice');
    Object.defineProperty(p1, 'name', {value:'alice2', writable:true, enumerable: false, configurable: false});
    console.log(p1.name); //=> alice2
    delete p1.name; //=> false
    configurable==flase,不能defineProperty重定义属性特性
    Object.defineProperty(p1, 'name', {value:'kk', enumerable: true}); //=>error
  

• Object.defineProperties(object, descriptors)

  var p1 = new Person('alice');
  
  Object.defineProperties(p1,{
  
  skill:{
  
  value: 'singing',
  
  writable: true,
  
  enumerable: true,
  
  configurable: false
  
  },
  
  age: {
  
  value: 18,
  
  writable: true,
  
  enumerable: true,
  
  configurable: false
  
  }
  
  });
  
  p1.age //18
  
  p1.skill //singing

• Object.getOwnPropertyDescriptor(obj, propertyName)
  
  获取自有属性的descriptor

    function Person (n){ this.name = n; }
    Person.prototype = {
    	constructor: Person,
    	hi: function(name){ console.log('hi,'+name);}
    };
    var p1 = new Person('alice');
    var nameDescriptor = Object.getOwnPropertyDescriptor(p1, 'name');//=>{value:'alice', enumerable: true, writable: true, configurable: true}
    var des = Object.getOwnPropertyDescriptor(p1, 'hi');//=>undefined
  

• Object.getOwnPropertyNames(obj)
  
  获取对象所有的自有属性名

    //接上
    p1.age = 11;
    var props = Object.getOwnPropertyNames(p1); //=> ['name', 'age']
  

• Object.preventExtensions(obj)
  
  禁止扩展对象，即不能添加属性到对象上。

    //接上
    Object.preventExtensions(p1);
    p1.home = 'HK';
    console.log(p1.home); //=> undefined
  

• Object.isExtensible(obj)
  
  判断对象是否可扩展

    //接上
    Object.isExtensible(p1);//=> false
  

• Object.seal(obj) , Object.isSealed(obj)
  
  若对象为isSeal状态则不能添加或删除属性, 但可以修改现有属性的值

    //接上
    Object.seal(p1);
    Object.isSealed(p1); //true
    delete p1.name;//=>false
    p1.like = 'shopping';
    console.log(p1.like); //=> undefined
  

• Object.freeze(obj) , Object.isFrozen(obj)
  
  冻结对象（不能添加或删除属性，不能修改现有属性) freeze -> seal -> configurable:false 限制的严格程度递减

    Object.freeze(p1);
    Object.isFrozen(p1); //=> true
    p1.name = 'alice2';
    console.log(p1.name); //=> alice
    p1.school = 'hkzw';
    console.log(p1.school); //=> undefined
  

• Object.getPrototypeOf(obj);
  
  获取对象的原型对象

    var proto = Object.getPrototypeOf(p1);//=>{constructor: Person, hi: function(){..}}
  

• Array.isArray(arg)

• [].indexOf(val,[pos])

• [].lastIndexOf(val, [pos])

• [].every(fn(v, i, arr),[context])

• [].some(fn(v,i, arr), [context])

• [].forEach(fn(v, i, arr), [context])

• [].filter(fn(v, i, arr), [context])

• [].map(fn(v, i, arr), [context]);

• [].reduce(fn(prev, curr, i, arr), [primitive]);

• [].reduceRight(fn(prev, curr, i, arr), [primitive]);

• new Date().toJSON()
  
  序列化日期对象 输出： "2016-03-14T07:36:09.602Z"

• String.prototype.trim
  
  删除字符串两端空格 (" touch ").trim(); => touch