JS delete an element in the array instance code

This article mainly shares with you a JS method to delete an element in an array. It has a good reference value and I hope it will be helpful to everyone. Let’s follow the editor to take a look, I hope it can help everyone.

Delete an element specified in the array

First, you can define a function for the JS array object to find the position of the specified element in the array. , that is, the index, the code is:

Array.prototype.indexOf = function(val) { 
for (var i = 0; i < this.length; i++) { 
if (this[i] == val) return i; 
} 
return -1; 
};

Then use the index to get the element, and use the js array's own inherent function to delete the element:

The code is:

Array.prototype.remove = function(val) { 
var index = this.indexOf(val); 
if (index > -1) { 
this.splice(index, 1); 
} 
};

In this way, such a function is constructed. For example, I have an array:

var emp = ['abs','dsf','sdf','fd']

If we want to delete 'fd', we can use:

emp.remove('fd');

Delete an item of the array

splice(index,len,[item]) Note: This method will change the original array.

splice has 3 parameters, it can also be used to replace/delete/add one or several values ​​in the array

index: array starting subscript len: replacement/delete length item :Replacement value, if the delete operation is performed, the item will be empty

For example: arr = ['a','b','c','d']

Delete

//删除起始下标为1，长度为1的一个值(len设置1，如果为0，则数组不变) 
var arr = ['a','b','c','d']; 
arr.splice(1,1); 
console.log(arr); 
//['a','c','d']; 
 
 
//删除起始下标为1，长度为2的一个值(len设置2) 
var arr2 = ['a','b','c','d'] 
arr2.splice(1,2); 
console.log(arr2); 
//['a','d']

Replace

##

//替换起始下标为1，长度为1的一个值为‘ttt'，len设置的1 
var arr = ['a','b','c','d']; 
arr.splice(1,1,'ttt'); 
console.log(arr);   
//['a','ttt','c','d'] 
 
 
var arr2 = ['a','b','c','d']; 
arr2.splice(1,2,'ttt'); 
console.log(arr2);   
//['a','ttt','d'] 替换起始下标为1，长度为2的两个值为‘ttt'，len设置的1

Add ---- len setting is 0, item is the added value

##

var arr = ['a','b','c','d']; 
arr.splice(1,0,'ttt'); 
console.log(arr);   
//['a','ttt','b','c','d'] 表示在下标为1处添加一项'ttt' 

After the delete method deletes the elements in the array, it will set the subscripted value to undefined, and the array The length will not change

var arr = ['a','b','c','d']; 
delete arr[1]; 
arr; 
//["a", undefined × 1, "c", "d"] 中间出现两个逗号，数组长度不变，有一项为undefined

Related recommendations:

PHP example code for deleting specified subscript elements in an array

5 JavaScript algorithms for deleting duplicate elements from an array

How to delete null elements from an array using PHP recursion

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