A brief discussion on several methods of checking whether an array contains a specified value in JavaScript

This article will introduce you to several methods in JavaScript to check whether an array contains a specified value. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

Array is one of the data structures often used in our programming. While working with arrays, we often need to find a specific value in the array, JavaScript includes some built-in methods to check if an array has a specific value or object.

Today, let’s take a look at how to check whether an array contains a specific value or element.

Check whether an array contains a value of a basic type

Arrya.includes() method

The simplest way to check an array value is to use include()Method, as shown below:

#This function returns a Boolean value indicating whether the value exists.

Arrya.indexOf() method

When you need to find the exact position of the element, you can use the indexOf(elem) method, which is in the specified array Search elem in and return the index of its first occurrence. If the array does not contain elem, return -1.

For example, we can find the first occurrence of grade in an array containing grade:

In the first instance, the element appears and its position is returned, in the second instance, the return value indicates that the element does not exist.

We can use this to easily change the code flow

Check if the object array contains an object

some() method

When searching for an object, include()checks whether the provided object reference matches an object reference in the array. This is not what we want, since objects can have the same fields and corresponding values, but different references.

We can use the some() method to search based on the contents of the object. some()The method accepts one parameter, accepts a callback function, executes each value in the array once, until it finds an element that meets the conditions set by the callback function, and returns true .

To understand it better, let’s look at some practical applications of some()

The callback function is in the first two Returns false in the first case, but true in the third case because the names match. Thereafter, some() suspends execution and returns true.

Summary

In this article, we introduced several ways to check whether an array contains a specified value in JavaScript.

We have introduced the include() function, which returns a boolean value when the value is present. What the function does is: if the value exists, it returns the index of the value; if it does not exist, it returns -1.

Finally, for objects, the some() function helps us search for the existence of an object based on its content.

I am Xiaozhi, I am going to wash the dishes, see you next time!

Original address: https://stackacabuse.com/javascript-check-if-array-contains-a-value-element/

Author: Abhilash Kakumanu

Translation address: https://blog.csdn.net/qq449245884/article/details/113534100

For more computer programming related knowledge, please visit: Programming Teaching! !

The above is the detailed content of A brief discussion on several methods of checking whether an array contains a specified value in JavaScript. For more information, please follow other related articles on the PHP Chinese website!