How to Validate an Input is Alphanumeric or not using JavaScript?

How to Validate an Input is Alphanumeric or not using JavaScript?

Last Updated : 11 Oct, 2024

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 RegExp

A 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);

Output

The 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);

Output

Valid alphanumeric input.

How to Validate an Input is Alphanumeric or not using JavaScript?

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PranchalKatiyar

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