Array.every(x=>x)是每一個(gè)都要滿足

Array.some(x=>x)是有一個(gè)滿足。

Array.find（findIndex)，返回符合條件的第一個(gè)值。

Array.filter（過(guò)濾成新的數(shù)組）

數(shù)組的方法分為兩類(lèi)

1）改變?cè)瓟?shù)組

push,pop,shift,unshift,sort,reverse,splice

2）不改變?cè)瓟?shù)組concat,join-->

split，toStringpush：從數(shù)組最后一位開(kāi)始加數(shù)據(jù)

pop:把數(shù)組最后一位剪切

shift:在數(shù)組最前一位剪切

unshift:在數(shù)組最前一位加數(shù)

reverse:把原數(shù)組逆轉(zhuǎn)

splice:arr.splice(從第幾位開(kāi)始，截取多少長(zhǎng)度，在切口處添加新數(shù)據(jù))

concat ：連接join:返回字符串

slice:截取arr.slice(從該為開(kāi)始截取，截取到該為)

示例

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.也可以通過(guò)上面方法過(guò)濾掉num為2的留下num為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)

4.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)

5.過(guò)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)

6.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]

7

/*  有一個(gè)對(duì)象數(shù)組 a ,將a數(shù)中對(duì)象某個(gè)屬性的值存儲(chǔ)到B數(shù)組中*/ var porducts = [  {name:"cucumber",type:"vegetable"},  {name:"banana",type:"fruit"},  {name:"celery",type:"vegetable"},  {name:"orange",type:"fruit"},];// es5var filteredProducts = [];for(var i = 0;i < porducts.length; i ++){  if(porducts[i].type === "fruit"){    // 如果條件滿足就把當(dāng)前的值推入    filteredProducts.push(porducts[i])  }}// console.log(filteredProducts)//0: {name: "banana", type: "fruit"}1: {name: "orange", type: "fruit"}length: 2__proto__: Array(0)// ES6 var filter2 = porducts.filter(function(porduct){//對(duì)porducts數(shù)組對(duì)象過(guò)濾如果porduct.type === "fruit"就return出去,再用一個(gè)變量接住  return porduct.type === "fruit"})console.log(filter2)