js-coding-challenges

Challenge 21: Validate Username

Write a function that checks if a given string is a valid username. A valid username should contain only alphanumeric characters and underscores, and should be between 4 and 16 characters long.

Write a function called isValidUsername that takes a string username in its parameter and returns true or false.

Answer

// Function to validate username
function isValidUsername(username) {
    // Regular expression pattern for username validation
    const regex = /^[a-zA-Z0-9_]{4,16}$/;

    // Test if the string matches the username pattern
    return regex.test(username);
}

Answer Explanation

The isValidUsername function takes a string as input and uses a regular expression to check if it’s a valid username. The regular expression ^[a-zA-Z0-9_]{4,16}$ is used to match the username pattern.

The test method is then used to check if the input string matches the regular expression, if it’s a valid username function returns true otherwise false.

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