function lowerCamelCase(snakeCase) {
    let capNext = false;
    const sb = [];
    for (let i = 0; i < snakeCase.length; i++) {
        let next = snakeCase.charAt(i);
        if (next == '_') {
            capNext = true;
        }
        else if (/\d/.test(next)) {
            sb.push(next);
            capNext = true;
        }
        else if (capNext) {
            sb.push(next.toUpperCase());
            capNext = false;
        }
        else if (i == 0) {
            sb.push(next.toLowerCase());
        }
        else {
            sb.push(next);
        }
    }
    return sb.join('');
}
Converts snake_case to lowerCamelCase.

Should behave like protoc:
https://github.com/protocolbuffers/protobuf/blob/e8ae137c96444ea313485ed1118c5e43b2099cf1/src/google/protobuf/compiler/java/java_helpers.cc#L118