JavaScript检测数组中是否存在满足某些条件的元素:

let arr = [2, 5, 8, 1, 4, 17, 89]// filter 实现let result = arr.filter(item => {    return item > 9}).length > 0// find 实现let result = arr.find(item => {    return item > 9})  !== undefined// some 实现let result =  arr.some(item => {    return item > 9})