How to Validate an Input is Alphanumeric or not using JavaScript? Last Updated : 11 Oct, 2024 Summarize Comments Improve Suggest changes Share Like Article Like Report To validate alphanumeric in JavaScript, regular expressions can be used to check if an input contains only letters and numbers. This ensures that the input is free from special characters.Approach: Using RegExpA RegExp is used to validate the input.RegExp is used to check the string of invalid characters that don't contain (a-z) alphabets and all numeric digits to validate.A not operator is used for the desired output.Example: This example implements the above approach. JavaScript let input = "validate1234@"; // Function to validate alphanumeric input function validateFunc(input) { let val = input.trim(); let RegEx = /^[a-z0-9]+$/i; let Valid = RegEx.test(val); if (Valid) { console.log("The input is valid and alphanumeric."); } else { console.log("The input is invalid. Only alphanumeric characters are allowed."); } } validateFunc(input); OutputThe input is invalid. Only alphanumeric characters are allowed. Example 2: A different RegExp is used to validate the input.RegExp is checking for the (a-z) alphabets and (0-9) digits to validate. JavaScript let inputValue = "Validate123"; // Function to validate if the input is alphanumeric function validateFunc(input) { let val = input.trim(); let isValid = /^[a-z0-9]+$/i.test(val); console.log(isValid ? "Valid alphanumeric input." : "Invalid input."); } validateFunc(inputValue); OutputValid alphanumeric input. Comment More infoAdvertise with us Next Article Validate a password using HTML and JavaScript P PranchalKatiyar Follow Improve Article Tags : JavaScript Web Technologies Similar Reads How to check a date is valid or not using JavaScript? To check if a date is valid or not in JavaScript, we have to know all the valid formats of the date. For ex - "YYYY/DD/MM", "DD/MM/YYYY", and "YYYY-MM-DD", etc. We have a given date format and we need to check whether the given format is valid or not according to the official and acceptable date for 3 min read How to Validate Email Address using RegExp in JavaScript? Validating an email address in JavaScript is essential for ensuring that users input a correctly formatted email. Regular expressions (RegExp) provide an effective and efficient way to check the email format.Why Validate Email Addresses?Validating email addresses is important for a number of reasons 3 min read How to check if a string is html or not using JavaScript? The task is to validate whether the given string is valid HTML or not using JavaScript. we're going to discuss a few techniques. Approach Get the HTML string into a variable.Create a RegExp which checks for the validation.RegExp should follow the rules of creating an HTML document. Example 1: In thi 2 min read How to Validate Decimal Numbers in JavaScript ? Validating user input is an essential aspect of Web Development. As a developer, when we are playing with the numeric inputs provided by the end-user, it is quite important to ensure that the input provided by the user is in the correct format. We can use the regular expression to Validate Decimal N 2 min read Validate a password using HTML and JavaScript Validating a password using HTML and JavaScript involves ensuring that user-entered passwords meet certain criteria, such as length, complexity, or character types (e.g., uppercase, lowercase, numbers, and symbols). This process enhances security by enforcing strong password requirements before form 2 min read JavaScript - How to Validate Form Using Regular Expression? To validate a form in JavaScript, you can use Regular Expressions (RegExp) to ensure that user input follows the correct format. In this article, we'll explore how to validate common form fields such as email, phone number, and password using RegExp patterns.1. Validating an Email AddressOne of the 4 min read Like