filter() 方法創(chuàng)建一個(gè)新的數(shù)組，新數(shù)組中的元素是通過檢查指定數(shù)組中符合條件的所有元素。

es6 filter()方法的用法

1、創(chuàng)建一個(gè)數(shù)組，判斷數(shù)組中是否存在某個(gè)值

var newarr = [   { num: 1, val: 'ceshi', flag: 'aa' },   { num: 2, val: 'ceshi2', flag: 'aa2'  } ] console.log(newarr.filter(item => item.num===2 ))

2、去掉空數(shù)組空字符串、undefined、null

var arr = ['1','2',undefined, '3.jpg',undefined] var newArr = arr.filter(item => item) console.log(newArr)  var arr = ['1','2',null, '3.jpg',null] var newArr = arr.filter(item => item) console.log(newArr)  //空字符串里面不能包含空格 var arr = ['1','2','', '3.jpg',''] var newArr = arr.filter(item => item) console.log(newArr)

3、去掉數(shù)組中不符合項(xiàng)

var arr = [20,30,50, 96,50] var newArr = arr.filter(item => item>40)   console.log(newArr)

4、過濾不符合項(xiàng)

var arr = ['10','12','23','44','42'] var newArr = arr.filter(item => item.indexOf('2')<0)  console.log(newArr)

5、數(shù)組去重

var arr = [1, 2, 2, 3, 4, 5, 5, 6, 7, 7,8,8,0,8,6,3,4,56,2]; var arr2 = arr.filter((x, index,self)=>self.indexOf(x)===index)   console.log(arr2); //[1, 2, 3, 4, 5, 6, 7, 8, 0, 56]

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