There are 4 ways to delete an element from a js array, namely: 1. Use splice; 2. Use filter; 3. Use the pop method and shift; 4. Use the delete keyword.
JavaScript is a programming language widely used in web development. It provides many methods for operating arrays. In JavaScript, there are many ways to delete elements from an array. Several commonly used methods will be introduced below.
1. Use the splice method
The splice method is a method that comes with JavaScript arrays. It can be used to delete elements in the array and return the deleted elements. . The splice method accepts two parameters. The first parameter is the starting position to be deleted, and the second parameter is the number of elements to be deleted. For example:
let arr = [1, 2, 3, 4, 5]; arr.splice(2, 1); // 删除从索引2开始的一个元素
The above code will delete element 3 with index 2 in the array arr. With the splice method, we can remove any number of elements at any position.
2. Use the filter method
The filter method is one of the higher-order functions of JavaScript arrays. It can filter the array according to a certain condition and return the results that match the condition. A new array composed of elements. We can use the filter method to filter out elements that do not need to be deleted, thereby achieving the effect of deleting elements. For example:
let arr = [1, 2, 3, 4, 5]; arr = arr.filter(element => element !== 3); // 删除数组中值为3的元素
The above code will delete the element with value 3 in array arr. By using the filter method, we can delete elements from the array based on different conditions.
3. Use pop method and shift method
The pop method and shift method are two methods used to delete the last element and the first element of the array. The pop method will delete the last element of the array and return the deleted element; the shift method will delete the first element of the array and return the deleted element. For example:
let arr = [1, 2, 3, 4, 5]; arr.pop(); // 删除数组的最后一个元素 arr.shift(); // 删除数组的第一个元素
The above code will delete the last element 5 and the first element 1 of the array arr.
4. Use the delete keyword
JavaScript provides the delete keyword for deleting the properties of an object, but it can also be used to delete elements in an array. When you use the delete keyword to delete an array element, the position of the deleted element will become undefined. For example:
let arr = [1, 2, 3, 4, 5]; delete arr[2]; // 删除数组中索引为2的元素
The above code will delete element 3 with index 2 in array arr and set the value of arr[2] to undefined.
Summary:
In JavaScript, there are many ways to delete elements in an array, including using the splice method, filter method, pop method, shift method and delete key Character. Which method to choose depends on the actual needs. Use the splice method to delete any number of elements at any position; use the filter method to filter out elements that do not need to be deleted based on conditions; use the pop method to delete the last element of the array; use the shift method to delete the first element of the array; use delete keyword can set the value of an array element to undefined. Master these methods to more flexibly operate elements in JavaScript arrays .
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