Generate Random Strings in JavaScript

function generateRandomString(length = 16, customChars = null) {
    const defaultChars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
    const chars = customChars || defaultChars;

    const array = new Uint32Array(length);
    crypto.getRandomValues(array);

    let result = '';
    for (let i = 0; i < length; i++) {
        result += chars[array[i] % chars.length];
    }

    return result;
}

// Generate a 16-character alphanumeric string
const randomString = generateRandomString(16);
console.log(randomString);  // Example: aB3xY7mN2pQ9zR5t

// Generate a 12-character hex string
const hexChars = '0123456789abcdef';
const hexString = generateRandomString(12, hexChars);
console.log(hexString);  // Example: a3f7b2e9c4d1

// Generate a 10-character lowercase string
const lowercaseString = generateRandomString(10, 'abcdefghijklmnopqrstuvwxyz');
console.log(lowercaseString);  // Example: xmkpqrstuv