目录
第一种:删除最后一个元素
pop 删除
var arr = [1,2,3,4,5] arr.pop() // arr => [1,2,3,4]slice 删除
var arr = [1,2,3,4,5] var new_arr = arr.slice(0, -1) // arr => [1,2,3,4,5] // new_arr => [1,2,3,4] var arr = [1,2,3,4,5] var new_arr = arr.slice(0, arr.length - 1) // arr => [1,2,3,4,5] // new_arr => [1,2,3,4]splice 删除
var arr = [1,2,3,4,5] var new_arr = arr.splice(-1) // arr => [1,2,3,4] // new_arr => [5] var arr = [1,2,3,4,5] var new_arr = arr.splice(-1, 1) // arr => [1,2,3,4] // new_arr => [5] var arr = [1,2,3,4,5] var new_arr = arr.splice(arr.length - 1) // arr => [1,2,3,4] // new_arr => [5] var arr = [1,2,3,4,5] var new_arr = arr.splice(arr.length - 1, 1) // arr => [1,2,3,4] // new_arr => [5]for 删除
var arr = [1,2,3,4,5] var new_arr = [] for (let i = 0, len = arr.length; i < len; i++) { if (i < len - 1) { new_arr.push(arr[i]) } } // arr => [1,2,3,4,5] // new_arr => [1,2,3,4]length 删除
var arr = [1,2,3,4,5] arr.length = arr.length - 1 // arr => [1,2,3,4]第二种: 删除第一个元素
shift 删除
var arr = [1,2,3,4,5] arr.shift() // arr => [2,3,4,5]slice 删除
var arr = [1,2,3,4,5] var new_arr = arr.slice(1) // arr => [1,2,3,4,5] // new_arr => [2,3,4,5]splice 删除
var arr = [1,2,3,4,5] var new_arr = arr.splice(0, 1) // arr => [2,3,4,5] // new_arr => [1]第三种:删除数组中某个指定下标的元素
splice 删除
var delete_index = 2 var arr = [1,2,3,4,5] // arr => [1,2,3,4,5] var new_arr = arr.splice(delete_index, 1) // new_arr => [3] // arr => [1,2,4,5]for 删除
var delete_index = 2, arr = [1,2,3,4,5], new_arr = [] for (let i = 0, len = arr.length; i < len; i++) { if (i != delete_index) { new_arr.push(arr[i]) } } // arr => [1,2,3,4,5] // new_arr => [1,2,4,5]注意:
1. 不可以使用 delete 方式删除数组中某个元素,此操作会造成稀疏数组,被删除的元素的为位置依然存在为empty,且数组的长度不变
2. 不可以使用 forEach 方法比对数组下标值,因为 forEach 在循环的时候是无序的
第四种:删除数组中某个指定元素的元素
splice 删除
var element = 2, arr = [1,2,3,4,5] arr.splice(arr.indexOf(2), 1) // arr => [1,3,4,5]
filter 删除
var arr = [1,2,3,4,5], element = 2 arr = arr.filter(item => item != element) // arr => [1,3,4,5]
forEach、map、for 删除
var arr = [1,2,3,4,5], element = 2, new_arr = [] arr.forEach(item => (item != element && new_arr.push(item))) // new_arr => [1,3,4,5] // map 同理 var arr = [1,2,3,4,5], element = 2, new_arr = [] for (let i = 0; i < arr.length; i++) { arr[i] != element && new_arr.push(arr[i]) } // new_arr => [1,3,4,5]
Set 删除
var arr = [1,2,3,4,5], element = 2 var new_set = new Set(arr) new_set.delete(element) var new_arr = [...new_set] // new_arr => [1,3,4,5]
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