Learn JS array on the official website of Liao Xuefeng

IndexOf () The position of a character

Slice    equivalent to a substring   slice of string

A = [' A ', ' B ', [+] (5) ["A", "B", 1, 2, 3]a.slice (0,3) (3) ["A", "B", 1]a.slice (3  ) (2) [2, 3]

Append pop () after push () is removed from the back

A.push (' h ')7A (7) ["A", "B", 1, 2, 3, 4, "H"]a.pop ()"H"A (6) ["A", "B", 1, 2, 3, 4]

Unshift () in front       of add shift () to delete the previous

A.unshift (7a) (7) [A, "a", "B", 1, 2, 3, 4]a.shift ()A (6) ["A", "B", 1, 2, 3, 4]

A.sort () sort

Reverse () Flip

splice(start, deleteCount, value, ...)  插入、删除或替换数组的元素      万能方法

                     obj.splice(n, 0 ,val) 指定位置插入元素                      obj.splice(n, 1 ,val) 指定位置替换元素                      obj.splice(n, 1 )     指定位置删除元素

A (6) [1, 2, 3, 4, "A", "B"]a.splice (2,0,8) []a (7) [1, 2, 8, 3, 4, "A", "B"]a.splice (2,1) [8]a (6) [1, 2, 3, 4, "A", "B"]a.splice (2,1,8) [3]a (6) [1, 2, 8, 4, "A", "B"]

Join () forms a string of array elements

a.join ()"1,2,8,4,a,b"

Learn JS array on the official website of Liao Xuefeng