删除
function cut(value) {
   return value.slice(0,value.length-1)
}

排序
let arr = [5,2,1,4,9,8] for(let i = 0 ; i < arr.length ; i ++) { for(let j = 0 ; j < arr.length -1 ; j ++) { if(arr[j] > arr[j+1]){ let num = arr[j] arr[j] = arr[j+1] arr[j+1] = num comeout.innerText = arr } }

 

// 升序arr.sort(function(a,b){return a - b})console.log(arr)
// 结果 1,2,4,5,8,9// 降序
arr.sort(function(a,b){return b - a})console.log(arr)
// 结果 9,8,5,4,2,1

let arr_choice = [{id:1},{id:3},{id:2},{id:8},{id:6},{id:4}]
// 升序
arr_choice.sort(function(a,b){return b.id - a.id})console.log(arr_choice)
// 结果：[{"id":1},{"id":2},{"id":3},{"id":4},{"id":6},{"id":8}]// 降序
arr_choice.sort(function(a,b){return b.id - a.id})console.log(arr_choice)
// 结果：[{"id":8},{"id":6},{"id":4},{"id":3},{"id":2},{"id":1}]

let arr_multi = [{id:1,age:10},{id:3,age:5},{id:2,age:6},{id:8,age:8},{id:6,age:5},{id:4,age:5}]
// 升序
arr_multi.sort(function(a,b){// 默认根据年龄排序，年龄相同则按照id排序if(a.age==b.age){return a.id - b.id}return a.age - b.age})console.log(arr_multi)
// 结果：[{"id":3,"age":5},{"id":4,"age":5},{"id":6,"age":5},{"id":2,"age":6},{"id":8,"age":8},{"id":1,"age":10}]// 降序arr_multi.sort(function(a,b){// 默认根据年龄排序，相同则按照id排序if(a.age==b.age){return b.id - a.id }return b.age - a.age })console.log(arr_multi)
// 结果：[{"id":1,"age":10},{"id":8,"age":8},{"id":2,"age":6},{"id":6,"age":5},{"id":4,"age":5},{"id":3,"age":5}]