自解释代码

summary

1. 使用命名常量而非晦涩的错误代码 | Using named constants instead of cryptic error codes
2. 将复杂逻辑抽离成独立函数 | Extracting complex logic and putting it in its own function
3. 运用短路求值使代码流程线性化 | Using short-circuit evaluation to make the code flow linear
4. 引入类型注解辅助静态检查与实时编码反馈 | Introducing type annotations to help with static type checking and real-time coding feedback

original code

async function createUser(user) {
    if (!validateUserInput(user)) {
        throw new Error('u105');
    }

    const rules = [/[a-z]{1,}/, /[A-Z]{1,}/, /[0-9]{1,}/, /\W{1,}/];
    if (user.password.length >= 8 && rules.every((rule) => rule.test(user.password))) {
        if (await userService.getUserByEmail(user.email)) {
            throw new Error('u212');
        }
    } else {
        throw new Error('u201');
    }

    user.password = await hashPassword(user.password);
    return userService.create(user);
}

命名常量与单一职责原则

const err = {
    userValidationFailed: 'u105',
    userExists: 'u212',
    invalidPassword: 'u201',
};

function isPasswordValid(password) {
    const rules = [/[a-z]{1,}/, /[A-Z]{1,}/, /[0-9]{1,}/, /\W{1,}/];
    return password.length >= 8 && rules.every((rule) => rule.test(password));
}

async function createUser(user) {
    if (!validateUserInput(user)) {
        throw new Error(err.userValidationFailed);
    }

    if (isPasswordValid(user.password)) {
        if (await userService.getUserByEmail(user.email)) {
            throw new Error(err.userExists);
        }
    } else {
        throw new Error(err.invalidPassword);
    }

    user.password = await hashPassword(user.password);
    return userService.create(user);
}

短路求值

function throwError(error) {
    throw new Error(error);
}

async function createUser(user) {
    validateUserInput(user) || throwError(err.userValidationFailed);
    isPasswordValid(user.password) || throwError(err.invalidPassword);
    !(await userService.getUserByEmail(user.email)) || throwError(err.userExists);

    user.password = await hashPassword(user.password);
    return userService.create(user);
}