JavaScript Clean Code 🛠

Use explanatory variables 💡

Bad :

const address = 'One Infinite Loop, Cupertino 95014';

const cityZipCodeRegex = /^[^,\\]+[,\\\s]+(.+?)\s*(\d{5})?$/;

saveCityZipCode(address.match(cityZipCodeRegex)[1], address.match(cityZipCodeRegex)[2]);

Good :

const address = 'One Infinite Loop, Cupertino 95014';

const cityZipCodeRegex = /^[^,\\]+[,\\\s]+(.+?)\s*(\d{5})?$/;

const [, city, zipCode] = address.match(cityZipCodeRegex) || [];

saveCityZipCode(city, zipCode);

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#JSTips #CleanCode
@ProgrammingTip

JavaScript Clean Code 🛠

We will read more code than we will ever write. It's important that the code we do write is readable and searchable.💡

Bad :

// What the heck is 86400000 for?
setTimeout(blastOff, 86400000);

Good :

// Declare them as capitalized `const` globals.
const MILLISECONDS_IN_A_DAY = 86400000;

setTimeout(blastOff, MILLISECONDS_IN_A_DAY);

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#JSTips #CleanCode
@ProgrammingTip

JavaScript Clean Code 🛠

Don't add unneeded context 💡
If your class/object name tells you something, don't repeat that in your variable name.

Bad :

const Car = {
  carMake: 'Honda',
  carModel: 'Accord',
  carColor: 'Blue'
};

function paintCar(car) {
  car.carColor = 'Red';
}

Good :

const Car = {
  make: 'Honda',
  model: 'Accord',
  color: 'Blue'
};

function paintCar(car) {
  car.color = 'Red';
}

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#JSTips #CleanCode
@ProgrammingTip

JavaScript Clean Code 🛠

Functions should do one thing 💡

Bad :

function emailClients(clients) {
  clients.forEach((client) => {
    const clientRecord = database.lookup(client);
    if (clientRecord.isActive()) {
      email(client);
    }
  });
}

Good :

function emailActiveClients(clients) {
  clients
    .filter(isActiveClient)
    .forEach(email);
}

function isActiveClient(client) {
  const clientRecord = database.lookup(client);
  return clientRecord.isActive();
}

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#JSTips #CleanCode
@ProgrammingTip

JavaScript Clean Code 🛠

Don't use flags as function parameters 💡

Bad :

function createFile(name, temp) {
  if (temp) {
    fs.create(`./temp/${name}`);
  } else {
    fs.create(name);
  }
}

Good :

function createFile(name) {
  fs.create(name);
}

function createTempFile(name) {
  createFile(`./temp/${name}`);
}

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#JSTips #CleanCode
@ProgrammingTip

JavaScript Clean Code 🛠

Avoid negative conditionals 💡

Bad :

function isDOMNodeNotPresent(node) {
  // ...
}

if (!isDOMNodeNotPresent(node)) {
  // ...
}

Good :

function isDOMNodePresent(node) {
  // ...
}

if (isDOMNodePresent(node)) {
  // ...
}

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#JSTips #CleanCode
@ProgrammingTip

JavaScript Clean Code 🛠

Use getters and setters 💡

Bad :

function makeBankAccount() {

  return {
    balance: 0,
    // ...
  };
}

const account = makeBankAccount();
account.balance = 100;

Good :

function makeBankAccount() {
  let balance = 0;

  function getBalance() {
    return balance;
  }

  function setBalance(amount) {
    balance = amount;
  }

  return {
    getBalance,
    setBalance,
  };
}

const account = makeBankAccount();
account.setBalance(100);

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#JSTips #CleanCode
@ProgrammingTip

JavaScript Clean Code 🛠

Async/Await are even cleaner than Promises 💡

Bad :

get('https://en.wikipedia.org/wiki/Robert_Cecil_Martin')
  .then((response) => {
    return writeFile('article.html', response);
  })
  .then(() => {
    console.log('File written');
  })
  .catch((err) => {
    console.error(err);
  });

Good :

async function getCleanCodeArticle() {
  try {
    const response = await get('https://en.wikipedia.org/wiki/Robert_Cecil_Martin');

    await writeFile('article.html', response);

    console.log('File written');
  } catch(err) {
    console.error(err);
  }
}

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#JSTips #CleanCode
@ProgrammingTip

JavaScript Clean Code 🛠

Only comment things that have business logic complexity. 💡
Comments are an apology, not a requirement. Good code mostly documents itself.

Bad :

function hashIt(data) {
  // The hash
  let hash = 0;

  // Length of string
  const length = data.length;

  // Loop through every character in data
  for (let i = 0; i < length; i++) {
    // Get character code.
    const char = data.charCodeAt(i);
    // Make the hash
    hash = ((hash << 5) - hash) + char;
    // Convert to 32-bit integer
    hash &= hash;
  }
}

Good :

function hashIt(data) {
  let hash = 0;
  const length = data.length;

  for (let i = 0; i < length; i++) {
    const char = data.charCodeAt(i);
    hash = ((hash << 5) - hash) + char;

    // Convert to 32-bit integer
    hash &= hash;
  }
}

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#JSTips #CleanCode
@ProgrammingTip

JavaScript Clean Code 🛠

Use consistent capitalization 💡

Bad :

const DAYS_IN_WEEK = 7;
const daysInMonth = 30;

const songs = ['Back In Black', 'Stairway to Heaven', 'Hey Jude'];
const Artists = ['ACDC', 'Led Zeppelin', 'The Beatles'];

function eraseDatabase() {}
function restore_database() {}

class animal {}
class Alpaca {}

Good :

const DAYS_IN_WEEK = 7;
const DAYS_IN_MONTH = 30;

const SONGS = ['Back In Black', 'Stairway to Heaven', 'Hey Jude'];
const ARTISTS = ['ACDC', 'Led Zeppelin', 'The Beatles'];

function eraseDatabase() {}
function restoreDatabase() {}

class Animal {}
class Alpaca {}

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#JSTips #CleanCode
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