1.创建一个数组,判断数组中是否存在某个值
var newarr = [
{
num: 1, val: 'ceshi', flag: 'aa' },
{
num: 2, val: 'ceshi2', flag: 'aa2' }
]
console.log(newarr.filter(item => item.num===2 ))
2.也可以通过上面方法过滤掉num为2的留下num为1的
var newarr = [
{
num: 1, val: 'ceshi', flag: 'aa' },
{
num: 2, val: 'ceshi2', flag: 'aa2' }
]
console.log(newarr.filter(item => item.num!=2 ))
3..去掉空数组空字符串、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)
>
var arr = ['1','2','', '3.jpg','']
var newArr = arr.filter(item => item)
console.log(newArr)
4.数组去重
var chognfu = [1,2,4,1,10,4,3,21]
var self = []
chognfu.filter((item)=>{
if(self.indexOf(item)==-1){
self.push(item)
}
})
console.log(self,'self')