CCC2 My runtime optimized and hopefully readable solution

My submission for the 2nd SAP Community Coding Challenge. Feel free to suggest improvements or point out bugs.

const getStartingNumberWithLongestChain = limit => {
    // Buffer the chain lengths in a prefilled array
    let chainLengthBuffer = new Uint32Array(limit);
    chainLengthBuffer[1] = 1;

    const getChainLength = number => {
        let n = number;
        let chainLength = 0;
        // Calculate till the buffer is reached, the remaining
        // length can be read from buffer
        // The buffer is prefilled at index 1, which is always
        // the last number of the chain
        while (!chainLengthBuffer[n]) {
            // Bitwise n % 2 === 1
            if (n & 1) {
                // If you multiply an odd number with an odd
                // number, you get an odd number
                // Odd number + 1 = even number
                // => you can do odd and then even without
                // checking odd or even in between
                n = 3 * n + 1;
                chainLength++;
            }          
            n /= 2;
            chainLength++;
        }
        chainLength += chainLengthBuffer[n];
        // Add result to buffer
        chainLengthBuffer[number] = chainLength;
        return chainLength;
    };

    let startingNumber = 1;
    let longestChainLength = 1;
    for (let i = 1; i < limit; i++) {
        const chainLength = getChainLength(i);
        if (chainLength > longestChainLength) {
            longestChainLength = chainLength;
            startingNumber = i;
        }
    }
    return startingNumber;
};

console.log(getStartingNumberWithLongestChain(1000000));

The answer is: 837799

Click here for a runnable version with proper syntax highlighting: https://repl.it/@AlexMFrank/ccc2