What are the methods to delete array elements in javascript

Delete method: 1. length attribute, delete elements from the end of the array; 2. delete keyword, syntax "delete array name [subscript];"; 3. pop() stack method; 4. shift( ) queue method; 5. splice() function, syntax "splice (starting position, number of deletions)".

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

In JavaScript, besides Object, the Array type (array) is probably the most commonly used type. Arrays in JavaScript are very flexible compared to arrays in other languages. This kind of flexibility has advantages and disadvantages. The advantage is that it is creative and can provide various flexible solutions; the disadvantage is that it is easy to be brainless, because in fact, it is too flexible, and it is so flexible that it is uncontrollable and crazy.

After teasing a few words before, let’s get back to the topic. Here are 5 ways to delete Array elements in JavaScript, namely using the length attribute, delete keyword, pop() stack method, and shift() queue method. , splice() operation method.

length attribute

The length attribute of Array in JavaScript is very unique—it is not read-only. Therefore, you can set this property to remove items from the end of the array or add new items.

var colors = ["red", "blue", "grey"]; // 创建一个包含3个字符串的数组
colors.length = 2;

console.log(colors[2]); // undefined

delete keyword

JavaScript provides a delete keyword to delete (clear) array elements.

var colors = ["red", "blue", "grey", "green"];
delete colors[0];

console.log(colors); // [undefined, "blue", "grey", "green"]

It should be noted that after using delete to delete an element, the length of the array does not change, but the deleted element is set to undefined.

pop() stack method

The Array object in JavaScript provides a pop() stack method for popping and returning elements in the array The last item can be used as a deletion to some extent.

The access rule of the stack data structure is FILO (First In Last Out). The stack operation adds items to the top of the stack and removes items from the top of the stack. Use the pop() method, which can remove The last item in the array and returns that item, decrementing the length of the array by one.

var colors = ["red", "blue", "grey"];
var color = colors.pop();

console.log(color); // "grey"
console.log(colors.length); // 2

It can be seen that when the pop() method is called, the array returns the last item, which is "grey", and there are only two elements left in the array.

shift() queue method

The Array object in JavaScript provides a shift() queue method for popping and returning elements in the array The first item can also be used as a deletion to some extent.

The access rule of the queue data structure is FIFO (First In First Out). The queue adds items at the end of the list and removes items from the front of the list. Using the shift() method, it can move Divide the first item in the array and return that item, and reduce the length of the array by one.

var colors = ["red", "blue", "grey"];
var color = colors.shift();

console.log(color); // "red"
console.log(colors.length); // 2

It can be seen that when the shift() method is called, the array returns the first item, which is "red", and there are only two elements left in the array.

splice() operation method

The JavaScript Array object provides a splice() method for performing specific operations on the array. . splice() is probably the most powerful array method. It can be used in many ways. Here we only introduce the method of deleting array elements. When deleting array elements, it can delete any number of items by specifying only 2 parameters: the position of the first item to be deleted and the number of items to be deleted.

var colors = ["red", "blue", "grey"];
var color = colors.splice(0, 1);

console.log(color); // "red"
console.log(colors); // ["blue", "grey"]

It can be seen that when the splice(0, 1) method is called, one item is deleted from the array starting from the first item.

[Recommended learning: javascript advanced tutorial]

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