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This time I will bring you a detailed explanation of the use of the js array prototype method. What are the precautions for using the js array prototype method? The following is a practical case, let's take a look.
push will change the original array, the return value is the changed array length
var arr = [1,2,3]; var length = arr.push(4,5) console.log('length: ' + length + ' arr: ' + arr) // length: 5 arr: 1,2,3,4,5pop
will change the original array, the return value is the popped element value
var arr = [1,2,3]; var val = arr.pop() console.log('val: ' + val + ' arr: ' + arr) // val: 3 arr: 1,2unshift
will change the original array, and the return value is the changed array length
var arr = [1,2,3]; var length = arr.unshift('haha') console.log('length : ' + length + ' arr: ' + arr) // length : 4 arr: haha,1,2,3shift
will change the original array, and the return value is the shifted element value
var arr = [1,2,3]; var val = arr.shift() console.log('val: ' + val + ' arr: ' + arr) // val: 1 arr: 2,3concat
will not change the original array, the return value is a new array
var arr = [1,2,3]; var arr1 = arr.concat(['haha','hehe']) console.log('arr : ' + arr + ' arr1: ' + arr1) // arr : 1,2,3 arr1: 1,2,3,haha,hehereverse
will change the original array, the return value is the original array
var arr = [1,2,3]; var arr1 = arr.reverse(); // [3,2,1] console.log('arr: ' + arr + ' arr1: ' + arr1) // arr: 3,2,1 arr1: 3,2,1slice( start, end)
Select some elements from the original array (the subscripts are elements from start to end-1) to form a new array. Both start and end can be negative numbers. The stipulation is to count from the end of the array. -1 refers to the last element, -2 refers to the second to last element, and so on.
will not change the original array, and the return value is a new array.
// 有end var arr = [1,2,3,4]; var arr1 = arr.slice(1,3); // 1:起始下标,3:结束下标 console.log('arr: ' + arr + ' arr1: ' + arr1) // arr: 1,2,3,4 arr1: 2,3 // 无end,那么切分的数组包含从 start 到数组结束的所有元素 var arr = [1,2,3,4]; var arr1 = arr.slice(1); // 1:起始下标 console.log('arr: ' + arr + ' arr1: ' + arr1) // arr: 1,2,3,4 arr1: 2,3,4 // end为负数 var arr = [1,2,3,4]; var arr1 = arr.slice(1, -2); console.log('arr: ' + arr + ' arr1: ' + arr1) // arr: 1,2,3,4 arr1: 2 // start为负数 var arr = [1,2,3,4]; var arr1 = arr.slice(-3, -2); console.log('arr: ' + arr + ' arr1: ' + arr1) // arr: 1,2,3,4 arr1: 2splice()
Delete , insert and replace the original array. Returning an array composed of deleted items will change the original array, and the return value is a new array
// 删除 var arr = [1,2,3,4,5]; var arr1 = arr.splice(1,2); // 1:起始下标,2:删除的项数 console.log('arr: ' + arr + ' arr1: ' + arr1) // arr: 1,4,5 arr1: 2,3 // 插入 var arr = [1,2,3,4,5]; var arr1 = arr.splice(1,0,'a','b'); // 1:起始下标(在此下标之前插入),0:不删除,'a'和'b'是要插入的元素 console.log('arr: ' + arr + ' arr1: ' + arr1) // arr: 1,a,b,2,3,4,5 arr1: [] // 替换 var arr = [1,2,3,4,5]; var arr1 = arr.splice(1,2,'a','b','c'); // 1:起始下标,2:删除的项数,'a','b','c'是要插入的元素 console.log('arr: ' + arr + ' arr1: ' + arr1) // arr: 1,a,b,c,4,5 arr1: 2,3I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other php Chinese websites related articles! Recommended reading:
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