gistfile1.txt

function is_extension_of(extension, original) {
    if (original.length > extension.length) {
        return false;
    }

    let j = 0; 
    for (let i = 0; i < extension.length; i++) {
        if (extension[i] === original[j]) {
            j++;
        }

        if (j === original.length) {
            return true;
        }
    }

    return j === original.length;
}