Native JS---3

Native js study notes 3 - array

　Define array

　Two ways to define an array:

　1. var array1 = new array(1, 2, 3, 4);

　2. var array2 = [1, 2, 3, 4];

　Insertion and deletion of array elements

　• push(element): Add new elements from the end

　• unshift(element): Add new elements from the head

　• pop(), pop element from the tail

　• shift(), pop the element from the head

　Delete several elements continuously from a certain position

　splice(starting position, length) This method starts from the starting position and deletes length elements

　Insertion of array elements Insert several elements

　splice(starting position, 0, element to be inserted 1, element to be inserted 2, element to be inserted 3...) Delete 0 elements from the starting position, and then insert the element to be inserted from the starting position Enter array

　Replacement of array elements

　splice(starting position of the element to be replaced, length of the element to be replaced, newly replaced element 1, newly replaced element 2...)

　Sorting of arrays

The sort() method can sort the array (sort according to the order of the ASICC table)

　Sort the string array:

        var aArray = ["a", "b", "c", "a", "d"];

aArray.sort();

alert(aArray);

Sorting an integer array

　 Numbers cannot be sorted using the sort() method, so we need to pass a function to the parameter part of the sort method, which has achieved our purpose (this is similar to the meaning of sorting arrays in OC)

        var aArray = [2,13,21,12,23,45,23];

aArray.sort(function(num1,num2) {

                                                                                                                                                                     })

alert(aArray);

　

Splicing of arrays

　The concat() method can realize the splicing of two arrays

var

aArr1 = [1,2,3,4];

var

aArr2 = [5,6,7,8];

var

aArr3 = aArr1.concat(aArr2);

alert(aArr3);

Execution effect:

　Add separators between array elements

　The join() method can use the parameters in parentheses as element separators in the array

Execution effect: