javascript splice() method can be used to delete a specified number of elements, replace a specified element, and add an element at a specified position, using the syntax "array.splice(index,count,item1,...,itemX )".
The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.
javascript splice method
In javascript, the splice() method is used to add or remove elements from an array.
Syntax:
array.splice(index,count,item1,.....,itemX)
| Parameters | Description |
|---|---|
| index | Required. Specifies where to add/remove elements. This parameter is the subscript of the array element to start inserting and/or deleting, and must be a number. |
| coun | Optional. Specifies how many elements should be removed. Must be a number, but can be "0". If this parameter is not specified, all elements starting from index to the end of the original array will be deleted. |
| item1, ..., itemX | Optional. The new element to be added to the array |
splice() method is relatively powerful. It can delete a specified number of elements, replace a specified element, and add an element at a specified position. The implementation of these different functions needs to be determined in combination with the method parameters:
When the parameters have only two parameters, index and count, if count is not equal to 0, the splice() method implements the deletion function, and at the same time Return the deleted elements: delete the number of elements specified by the count parameter starting from the position specified by the index parameter;
When there are more than 3 parameters and the count parameter is not 0, splice( ) method implements the replacement function and returns the replaced element at the same time: replace the number of elements specified by the count parameter starting at the position specified by the index parameter with the third and subsequent parameters;
When When there are more than 3 parameters and the count parameter is 0, the implementation of the splice() method adds the function of adding the third and subsequent parameters to the position specified by the index parameter.
Return value: array type; if an element is deleted from array, the array containing the deleted element is returned.
Examples of each function implemented by the splice() method are as follows:
① Use splice() to delete a specified number of elements from a specified position:
var arr = ['A','B','C','D']; //2个参数，第二个参数不为 0，实现删除功能 alert(arr.splice(0,2)); alert(arr); //返回C,D
② Use splice() Replace the specified number of elements starting from the specified position with the specified element:
var arr = ['A','B','C','D']; //3个参数，第二个参数不为 0，实现替换功能：用 a 替换掉 A，返回：A alert(arr.splice(0,1,'a')); alert(arr); //返回:a,B,C,D alert(arr.splice(0,2,'a or b'));//用a or b替换掉a和B，返回a,B alert(arr); //返回：a or b,C,D
③ Use splice() to add the specified element at the specified position:
var arr = ['A','B','C','D']; //4个参数，第二个参数为 0，实现添加功能：在下标为 1 处添加 aaa,bbb，没有返回值 alert(arr.splice(1,0,'aaa','bbb')); alert(arr);//返回：A,aaa,bbb,B,C,D
Example: Use the splice() method to implement Array deduplication.
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>使用splice方法实现数组去重</title>
<script>
var arr = [1,2,2,2,4,2];
for(var i = 0; i < arr.length; i++){
for(var j = i + 1; j < arr.length; j++){
if(arr[i] == arr[j]){
arr.splice(j,1);//删除 j 位置处的元素
j--;
}
}
}
alert(arr);//返回1,2,4三个元素
</script>
</head>
<body>
</body>
</html>The above code uses splice() with two parameters to implement the function of deleting specified elements.
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