stringToBase64

function stringToBase64(inputString) {
    // Define the Base64 character mapping
    const base64Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

    // Filter out non-alphanumeric characters and whitespace
    const filteredString = inputString.replace(/[^a-zA-Z0-9\s]/g, "");

    // Initialize variables
    const result = [];
    let currentBits = 0;
    let numBits = 0;

    // Convert the filtered input string to bytes
    const utf8Bytes = unescape(encodeURIComponent(filteredString));

    // Iterate through each byte in the filtered input data
    for (const char of utf8Bytes) {
        // Convert the character to its Unicode code point
        const byte = char.charCodeAt(0);

        // Shift the currentBits left by 8 bits and add the new byte
        currentBits = (currentBits << 8) | byte;
        numBits += 8;

        // While we have at least 6 bits, extract and encode them
        while (numBits >= 6) {
            numBits -= 6;
            // Extract the top 6 bits
            const index = (currentBits >> numBits) & 0x3F;
            result.push(base64Chars[index]);
        }
    }

    // Handle any remaining bits (less than 6 bits)
    if (numBits > 0) {
        // Pad with zeros to make a multiple of 6 bits
        currentBits <<= 6 - numBits;
        const index = currentBits & 0x3F;
        result.push(base64Chars[index]);
    }

    // Add padding '=' characters if necessary
    while (result.length % 4 !== 0) {
        result.push('=');
    }

    // Join the Base64 characters to form the final encoded string
    const base64Data = result.join('');

    return base64Data;
}

// Example usage:
const inputString = "Hello, this is a string to be encoded in Base64. #$%^";
const base64Result = stringToBase64(inputString);
console.log("Base64 Encoded String:", base64Result);