every 方法，数组的每一项都满足条件时，才会返回true
let arr =[12,4,0,56,8]
let flag =arr.every((item)=>{
return item>1
})
console.log(flag) //false
some 方法，数组中有一项或者多项满足条件会返回true
let arr =[12,4,0,56,8]
let flag =arr.some((item)=>{
return item>1
})
console.log(flag) //true
filter 方法，返回满足条件的元素,返回的是个新数组不会改变原数组
let arr =[1,45,12,23,34]
let newArr = arr.filter(item=>{
item > 12
})
console.log(newArr) //[45,23,34]
