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

Last Updated : 11 Oct, 2024
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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.

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

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PranchalKatiyar
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