es6 filter方法的使用

    var obj = [
      {
        id:1,
        name:'张三',
        beizhu:'123asd'
      },
      {
        id:2,
        name:'李四',
        beizhu:'122fghasd'
      },
      {
        id:3,
        name:'王五',
        beizhu:'12df4sd'
      },
    ]
    //取出数组对应的值
    console.log(obj.filter(item =>(item.id==1)))    
    //{id: 1, name: "张三", beizhu: "123asd"}
    //过滤数组中undefined，null，空字符串
    var arr1 = [1,'',undefined,null,'aaa']
     console.log(arr1.filter(item=>(item))) 
     //[1, "aaa"]
    //去除数组中不符合的值
    var arr2 = [2,40,5,100,8,90]
    console.log(arr2.filter(item=>(item>40)))   
    //[100, 90]
    //去掉数组中不符合项
    var arr3= [22,40,5,200,8,90]
    console.log(arr3.filter(item=> item.toString().indexOf(2)<0))   
    //[40, 5, 8, 90]
    // //数组去重
    var arr4 = [11,22,33,44,44,22,55]
    console.log(arr4.filter((num,index,list)=>list.indexOf(num) == index))   
    // [11, 22, 33, 44, 55]