join 数组转字符串，指定间隔符
var list=['a','b','c','d']
var str = list.join(",")
console.log(str)//a,b,c,d
pop 数组删除删除最后一个元素,返回删除的元素
var list=['a','b','c','d']
var p = list.pop()
console.log(p)//d
console.log(list)//['a','b','c']
shift 从数组中删除第一个元素,返回删除的元素
var s = list.shift()
console.log(s)//a
console.log(list)//['b','c']
push 数组结尾添加元素并返回新数组的长度
var list=['a','b','c']
var i = list.push('d');
console.log(i);//4
console.log(list)//['a','b','c','d']
unshift 数组开头添加元素并返回新数组的长度
var j = list.unshift('x')
console.log(j);//5
console.log(list)//['x','a','b','c','d']
splice(x,y) 第一个参数添加新元素的位置、第二个参数删除多少个元素
var list=['a','b','c']
//splice 向数组添加新元素
var a = list.splice(2, 0, "m", "n");
console.log(list)//['a','b','m','n','c']
//splice 删除元素
var list=['a','b','c']
var a = list.splice(0, 1)
console.log(a);//['a']
console.log(list)//['b','c']
concat 合并数组
var list1 = ['a','b']
var list2 = ['m','n']
var newList = list1.concat(list2)
console.log(list1)//['a','b']
console.log(newList)//['a','b','m','n']
slice 裁剪数组,返回新数组，它不会从原数组中删除任何元素
var list = ['a','b','c']
var newList = list.slice(1)
console.log(newList)//['b','c']
console.log(list)//['a','b','c']
var newList = list.slice(1,2)
console.log(newList)//['b']
console.log(list)//['a','b','c']
sort 排序，改变原数组
var points = [40, 100, 5, 25];
points.sort(function(a, b){return a - b});
console.log(points)//[5,25,40,100]
reverse 反转数组
points.reverse()
console.log(points)//[100,40,25,5]
forEach 数组遍历
var list =[1,2,3,4,5]
list.forEach(item=>{
console.log(item)
})
filter 数组过滤 ,不改变原数组，返回新数组
var nums = [45, 4, 9, 16, 25];
var over10 = nums.filter(item=>item>10)
console.log(nums)//[45, 4, 9, 16, 25]
console.log(over10)//[45, 16, 25]
some 检查某些数组值是否满足条件 返回true,false
var nums = [45, 4, 9, 16, 25];
var over10 = nums.some(item=>item>10)
console.log(over10)//true
indexOf 在数组中搜索元素值并返回其位置,没有返回-1
var nums = [45, 4, 9, 16, 25]
var idx = nums.indexOf(9)
console.log(idx)//2
var idx = nums.indexOf(10)
console.log(idx)//-1
find 返回满足条件的第一个数组元素的值,没有返回undefined
var nums = [45, 4, 9, 56, 25]
var mum = nums.find(item=>item>50)
console.log(mum)//56
findIndex 返回满足条件的第一个数组元素的索引，没有返回-1
var nums = [45, 4, 9, 56, 25]
var mum = nums.findIndex(item=>item>10)
console.log(mum)//0