Use meaningful and pronounceable variable names.

Bad:

const yyyymmdstr = moment().format('YYYY/MM/DD');

Good:

const currentDate = moment().format('YYYY/MM/DD');

INTRO TO CLEAN CODE IN JS

Use the same vocabulary for the same type of variable

Bad:

getUserInfo();
getClientData();
getCustomerRecord();

Good:

getUser();

INTRO TO CLEAN CODE IN JS

Use searchable names

We will read more code than we will ever write. It's important that the code we do write is readable and searchable. By notnaming variables that end up being meaningful for understanding our program, we hurt our readers.  Make your names searchable.

INTRO TO CLEAN CODE IN JS

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);

INTRO TO CLEAN CODE IN JS

Avoid Mental Mapping

Explicit is better than implicit.

Bad:

const locations = ['Austin', 'New York', 'San Francisco'];
locations.forEach((l) => {
  doStuff();
  doSomeOtherStuff();
  // ...
  // ...
  // ...
  // Wait, what is `l` for again?
  dispatch(l);
});

INTRO TO CLEAN CODE IN JS

Avoid Mental Mapping

Explicit is better than implicit.

INTRO TO CLEAN CODE IN JS

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';
}

INTRO TO CLEAN CODE IN JS

Use default arguments instead of short circuiting or conditionals

Bad:

function createMicrobrewery(name) {
  const breweryName = name || 'Hipster Brew Co.';
  // ...
}

Good:

function createMicrobrewery(breweryName = 'Hipster Brew Co.') {
  // ...
}

INTRO TO CLEAN CODE IN JS

Function arguments (2 or fewer ideally)

Bad:

function createMenu(title, body, buttonText, cancellable) {
  // ...
}

INTRO TO CLEAN CODE IN JS

Function arguments (2 or fewer ideally)

Good:

function createMenu({ title, body, buttonText, cancellable }) {
  // ...
}

createMenu({
  title: 'Foo',
  body: 'Bar',
  buttonText: 'Baz',
  cancellable: true
});

INTRO TO CLEAN CODE IN JS

FUNCTIONS SHOULD DO ONE THING

INTRO TO CLEAN CODE IN JS

Function names should say what they do

Bad:

function addToDate(date, month) {
  // ...
}

const date = new Date();

// It's hard to to tell from the function name what is added
addToDate(date, 1);

Good:

function addMonthToDate(date, month) {
  // ...
}

const date = new Date();
addMonthToDate(date, 1);

INTRO TO CLEAN CODE IN JS

Bad:

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

INTRO TO CLEAN CODE IN JS

Good:

function emailClients(clients) {
  clients
    .filter(isClientActive)
    .forEach(email);
}

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

INTRO TO CLEAN CODE IN JS

FUNCTIONS SHOULD ONLY

BE ONE LEVEL OF ABSTRACTION

INTRO TO CLEAN CODE IN JS

Bad:

function parseBetterJSAlternative(code) {
  const REGEXES = [
    // ...
  ];

  const statements = code.split(' ');
  const tokens = [];
  REGEXES.forEach((REGEX) => {
    statements.forEach((statement) => {
      // ...
    });
  });

  const ast = [];
  tokens.forEach((token) => {
    // lex...
  });

  ast.forEach((node) => {
    // parse...
  });
}

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

Good:

function tokenize(code) {
  const REGEXES = [
    // ...
  ];

  const statements = code.split(' ');
  const tokens = [];
  REGEXES.forEach((REGEX) => {
    statements.forEach((statement) => {
      tokens.push( /* ... */ );
    });
  });

  return tokens;
}

function lexer(tokens) {
  const ast = [];
  tokens.forEach((token) => {
    ast.push( /* ... */ );
  });

  return ast;
}

function parseBetterJSAlternative(code) {
  const tokens = tokenize(code);
  const ast = lexer(tokens);
  ast.forEach((node) => {
    // parse...
  });
}

Remove duplicate code

Do your absolute best to avoid duplicate code. Duplicate code is bad because it means that there's more than one place to alter something if you need to change some logic.

INTRO TO CLEAN CODE IN JS

Bad:

function showDeveloperList(developers) {
  developers.forEach((developer) => {
    const expectedSalary = developer.calculateExpectedSalary();
    const experience = developer.getExperience();
    const githubLink = developer.getGithubLink();
    const data = {
      expectedSalary,
      experience,
      githubLink
    };

    render(data);
  });
}

INTRO TO CLEAN CODE IN JS

function showManagerList(managers) {
  managers.forEach((manager) => {
    const expectedSalary = manager.calculateExpectedSalary();
    const experience = manager.getExperience();
    const portfolio = manager.getMBAProjects();
    const data = {
      expectedSalary,
      experience,
      portfolio
    };

    render(data);
  });
}

INTRO TO CLEAN CODE IN JS

Good:

function showList(employees) {
  employees.forEach((employee) => {
    const expectedSalary = employee.calculateExpectedSalary();
    const experience = employee.getExperience();

    let portfolio = employee.getGithubLink();

    if (employee.type === 'manager') {
      portfolio = employee.getMBAProjects();
    }

    const data = {
      expectedSalary,
      experience,
      portfolio
    };

    render(data);
  });
}

Set default objects with Objects.assign

INTRO TO CLEAN CODE IN JS

Set default objects with Objects.assign

INTRO TO CLEAN CODE IN JS

Good:

const menuConfig = {
  title: 'Order',
  // User did not include 'body' key
  buttonText: 'Send',
  cancellable: true
};

function createMenu(config) {
  config = Object.assign({
    title: 'Foo',
    body: 'Bar',
    buttonText: 'Baz',
    cancellable: true
  }, config);

  // config now equals: {title: "Order", body: "Bar", buttonText: "Send", cancellable: true}
  // ...
}

createMenu(menuConfig);

Flags tell your user that this function does more than one thing. Functions should do one thing. Split out your functions if they are following different code paths based on a boolean.

INTRO TO CLEAN CODE IN JS

Bad:

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

INTRO TO CLEAN CODE IN JS

AVOID SIDE EFFECTS (PART 1)

A function produces a side effect if it does anything other than take a value in and return another value or values. A side effect could be writing to a file, modifying some global variable, or accidentally wiring all your money to a stranger.

INTRO TO CLEAN CODE IN JS

Bad:

// Global variable referenced by following function.
// If we had another function that used this name, now it'd be an array and it could break it.
let name = 'Ryan McDermott';

function splitIntoFirstAndLastName() {
  name = name.split(' ');
}

splitIntoFirstAndLastName();

console.log(name); // ['Ryan', 'McDermott'];

INTRO TO CLEAN CODE IN JS

AVOID SIDE EFFECTS (PART 2)

In JavaScript, primitives are passed by value and objects/arrays are passed by reference. In the case of objects and arrays, if our function makes a change in a shopping cart array, for example, by adding an item to purchase, then any other function that uses that cart array will be affected by this addition. That may be great, however, it can be bad too.

INTRO TO CLEAN CODE IN JS

Bad:

const addItemToCart = (cart, item) => {
  cart.push({ item, date: Date.now() });
};

Good:

const addItemToCart = (cart, item) => {
  return [...cart, { item, date : Date.now() }];
};

INTRO TO CLEAN CODE IN JS

Polluting globals is a bad practice in JavaScript because you could clash with another library and the user of your API would be none-the-wiser until they get an exception in production.  

INTRO TO CLEAN CODE IN JS

Bad:

Array.prototype.diff = function diff(comparisonArray) {
  const hash = new Set(comparisonArray);
  return this.filter(elem => !hash.has(elem));
};

Good:

class SuperArray extends Array {
  diff(comparisonArray) {
    const hash = new Set(comparisonArray);
    return this.filter(elem => !hash.has(elem));
  }
}

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

Bad:

const programmerOutput = [
  {
    name: 'Uncle Bobby',
    linesOfCode: 500
  }, {
    name: 'Suzie Q',
    linesOfCode: 1500
  }, {
    name: 'Jimmy Gosling',
    linesOfCode: 150
  }, {
    name: 'Gracie Hopper',
    linesOfCode: 1000
  }
];

let totalOutput = 0;

for (let i = 0; i < programmerOutput.length; i++) {
  totalOutput += programmerOutput[i].linesOfCode;
}

INTRO TO CLEAN CODE IN JS

Good:

const programmerOutput = [
  {
    name: 'Uncle Bobby',
    linesOfCode: 500
  }, {
    name: 'Suzie Q',
    linesOfCode: 1500
  }, {
    name: 'Jimmy Gosling',
    linesOfCode: 150
  }, {
    name: 'Gracie Hopper',
    linesOfCode: 1000
  }
];

const INITIAL_VALUE = 0;

const totalOutput = programmerOutput
  .map((programmer) => programmer.linesOfCode)
  .reduce((acc, linesOfCode) => acc + linesOfCode, INITIAL_VALUE);

INTRO TO CLEAN CODE IN JS

Encapsulate conditionals

INTRO TO CLEAN CODE IN JS

Avoid negative conditionals

INTRO TO CLEAN CODE IN JS

AVOID CONDITIONALS

A function should only do one thing. When you have classes and functions that have if statements, you are telling your user that your function does more than one thing. Remember, just do one thing.

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

AVOID TYPE-CHECKING (PART 1)

JavaScript is untyped, which means your functions can take any type of argument. Sometimes you are bitten by this freedom and it becomes tempting to do type-checking in your functions. There are many ways to avoid having to do this. The first thing to consider is consistent APIs.

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

AVOID TYPE-CHECKING (PART 2)

If you are working with basic primitive values like strings, integers, and arrays, and you can't use polymorphism but you still feel the need to type-check, you should consider using TypeScript. It is an excellent alternative to normal JavaScript, as it provides you with static typing on top of standard JavaScript syntax. The problem with manually type-checking normal  is that doing it well requires so much extra verbiage that the faux "type-safety" you get doesn't make up for the lost readability. Keep your JavaScript clean, write good tests, and have good code reviews.

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

Modern browsers do a lot of optimization under-the-hood at runtime. A lot of times, if you are optimizing then you are just wasting your time. There are good resources for seeing where optimization is lacking. Target those in the meantime, until they are fixed if they can be.

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

REMOVE DEAD CODE

Dead code is just as bad as duplicate code. There's no reason to keep it in your codebase. If it's not being called, get rid of it! It will still be safe in your version history if you still need it.

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

USE GETTERS AND SETTERS

JavaScript doesn't have interfaces or types so it is very hard to enforce this pattern, because we don't have keywords like public and private. As it is. using getters and setters to access data on objects is far better than simply looking for a property on an object. "Why?" you might ask. Well, here's an unorganized list of reasons why.

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

const bankAccount = new BankAccount();

// Buy shoes...
bankAccount.balance -= shoesPrice;

// Get balance
let balance = bankAccount.balance;

Make objects have private members

This can be accomplished through closures.

Bad:

const Employee = function(name) {
  this.name = name;
};

Employee.prototype.getName = function getName() {
  return this.name;
};

const employee = new Employee('John Doe');
console.log(`Employee name: ${employee.getName()}`); // Employee name: John Doe
delete employee.name;
console.log(`Employee name: ${employee.getName()}`); // Employee name: undefined

INTRO TO CLEAN CODE IN JS

Make objects have private members

This can be accomplished through closures.

INTRO TO CLEAN CODE IN JS

SINGLE RESPONSIBILITY PRINCIPLE (SRP)

AS stated in Clean Code, "There should never be more than one reason for a class to change".  It's tempting to jam-pack a class with a lot of functionality, like when you can only take one suitcase on your flight. The issue with this is that your class won't be conceptually cohesive and it will give it many reasons to change. Minimizing the amount of times you need to change a class is important. It's important because if too much functionality is in one class and you modify a piece of it, it can be difficult to understand how that will affect other dependent modules in your codebase.  

INTRO TO CLEAN CODE IN JS

Bad:

class UserSettings {
  constructor(user) {
    this.user = user;
  }

  changeSettings(settings) {
    if (this.verifyCredentials()) {
      // ...
    }
  }

  verifyCredentials() {
    // ...
  }
}

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

Bad:

class AjaxAdapter extends Adapter {
  constructor() {
    super();
    this.name = 'ajaxAdapter';
  }
}

class NodeAdapter extends Adapter {
  constructor() {
    super();
    this.name = 'nodeAdapter';
  }
}

class HttpRequester {
  constructor(adapter) {
    this.adapter = adapter;
  }

INTRO TO CLEAN CODE IN JS

Good:

class AjaxAdapter extends Adapter {
  constructor() {
    super();
    this.name = 'ajaxAdapter';
  }

  request(url) {
    // request and return promise
  }
}

class NodeAdapter extends Adapter {
  constructor() {
    super();
    this.name = 'nodeAdapter';
  }

  request(url) {
    // request and return promise
  }
}

INTRO TO CLEAN CODE IN JS

THE LISKOV SUBSTITUTION PRINCIPLE (LSP)

INTRO TO CLEAN CODE IN JS

Bad:

class Rectangle {
  constructor() {
    this.width = 0;
    this.height = 0;
  }

  setColor(color) {
    // ...
  }

  render(area) {
    // ...
  }

  setWidth(width) {
    this.width = width;
  }

  setHeight(height) {
    this.height = height;
  }

  getArea() {
    return this.width * this.height;
  }
}

INTRO TO CLEAN CODE IN JS

Good:

class Shape {
  setColor(color) {
    // ...
  }

  render(area) {
    // ...
  }
}

class Rectangle extends Shape {
  constructor() {
    super();
    this.width = 0;
    this.height = 0;
  }

  setWidth(width) {
    this.width = width;
  }

  setHeight(height) {
    this.height = height;
  }​​​

 getArea() {
    return this.width * this.height;
  }
}

INTRO TO CLEAN CODE IN JS

INTERFACE SEGREGATION PRINCIPLE (ISP)

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

const $ = new DOMTraverser({
  rootNode: document.getElementsByTagName('body'),
  options: {
    animationModule() {}
  }
});

DEPENDENCY INVERSION PRINCIPLE (DIP)

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

  requestItems() {
    this.items.forEach((item) => {
      this.requester.requestItem(item);
    });
  }
}

const inventoryTracker = new InventoryTracker(['apples', 'bananas']);
inventoryTracker.requestItems();

Prefer ES2015/ES6 classes over ES5 plain functions

It's very difficult to get readable class inheritance, construction, and method definitions for classical ES5 classes. If you need inheritance (and be aware that you might not), then prefer classes. However, prefer small functions over classes until you find yourself needing larger and more complex objects.

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

class Human extends Mammal {
  constructor(age, furColor, languageSpoken) {
    super(age, furColor);
    this.languageSpoken = languageSpoken;
  }

  speak() { /* ... */ }
}

Use method chaining

This pattern is very useful in JavaScript and you see it in many libraries such as jQuery and Lodash. It allows your code to be expressive, and less verbose. For that reason, I say, use method chaining and take a look at how clean your code will be. In your class functions, simply return this at the end of every function, and you can chain further class methods onto it.

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

Prefer composition over inheritance

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

Testing is more important than shipping. If you have no tests or an inadequate amount, then every time you ship code you won't be sure that you didn't break anything. Deciding on what constitutes an adequate amount is up to your team, but having 100% coverage (all statements and branches) is how you achieve very high confidence and developer peace of mind. This means that in addition to having a great testing framework, you also need to use a good coverage tool.

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

Use promises

not callbacks.

Callbacks aren't clean, and they cause excessive amounts of nesting. With ES2015/ES6, Promises are a built-in global type. Use them!

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

Async/Await are even cleaner than Promises.

Promises are a very clean alternative to callbacks, but ES2017/ES8 brings async and await which offer an even cleaner solution. All you need is a function that is prefixed in an async keyword, and then you can write your logic imperatively without a then chain of functions. Use this if you can take advantage of ES2017/ES8 features today!

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

Thrown errors are a good thing! They mean the runtime has successfully identified when something in your program has gone wrong and it's letting you know by stopping function execution on the current stack, killing the process (in Node), and notifying you in the console with a stack trace.

DON'T IGNORE CAUGHT ERRORS

Doing nothing with a caught error doesn't give you the ability to ever fix or react to said error. Logging the error to the console (console.log) isn't much better as often times it can get lost in a sea of things printed to the console. If you wrap any bit of code in a try/catch it means you think an error may occur there and therefore you should have a plan, or create a code path, for when it occurs.

INTRO TO CLEAN CODE IN JS

INTRO TO CLEAN CODE IN JS

Don't ignore rejected promises

Bad:

getdata()
.then((data) => {
  functionThatMightThrow(data);
})
.catch((error) => {
  console.log(error);
});

Good:

getdata()
.then((data) => {
  functionThatMightThrow(data);
})
.catch((error) => {
  // One option (more noisy than console.log):
  console.error(error);
  // Another option:
  notifyUserOfError(error);
  // Another option:
  reportErrorToService(error);
  // OR do all three!
});

INTRO TO CLEAN CODE IN JS

Formatting is subjective. Like many rules herein, there is no hard and fast rule that you must follow. The main point is DO NOT ARGUE over formatting. There are tons of tools to automate this. Use one!

For things that don't fall under the purview of automatic formatting (indentation, tabs vs. spaces, double vs. single quotes, etc.) look here for some guidance.

Use consistent capitalization

JavaScript is untyped, so capitalization tells you a lot about your variables, functions, etc. These rules are subjective, so your team can choose whatever they want. The point is, no matter what you all choose, just be consistent.

INTRO TO CLEAN CODE IN JS

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 {}

INTRO TO CLEAN CODE IN JS

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 {}

INTRO TO CLEAN CODE IN JS

FUNCTION CALLERS AND CALLEES SHOULD BE CLOSE

If a function calls another, keep those functions vertically close in the source file. Ideally, keep the caller right above the callee. We tend to read code from top-to-bottom, like a newspaper. Because of this, make your code read that way.

INTRO TO CLEAN CODE IN JS

Bad:

class PerformanceReview {
  constructor(employee) {
    this.employee = employee;
  }

  lookupPeers() {
    return db.lookup(this.employee, 'peers');
  }

  lookupManager() {
    return db.lookup(this.employee, 'manager');
  }

  getPeerReviews() {
    const peers = this.lookupPeers();
    // ...
  }

  perfReview() {
    this.getPeerReviews();
    this.getManagerReview();
    this.getSelfReview();
  }

  getManagerReview() {
    const manager = this.lookupManager();
  }

  getSelfReview() {
    // ...
  }
}

const review = new PerformanceReview(user);
review.perfReview();

INTRO TO CLEAN CODE IN JS

Good:

class PerformanceReview {
  constructor(employee) {
    this.employee = employee;
  }

  perfReview() {
    this.getPeerReviews();
    this.getManagerReview();
    this.getSelfReview();
  }

  getPeerReviews() {
    const peers = this.lookupPeers();
    // ...
  }

  lookupPeers() {
    return db.lookup(this.employee, 'peers');
  }

  getManagerReview() {
    const manager = this.lookupManager();
  }

  lookupManager() {
    return db.lookup(this.employee, 'manager');
  }

  getSelfReview() {
    // ...
  }
}

const review = new PerformanceReview(employee);
review.perfReview();

INTRO TO CLEAN CODE IN JS

Only comment things that has business logic complexity.

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;
  }
}

INTRO TO CLEAN CODE IN JS

Don't leave commented out code in your codebase

Bad:

doStuff();
// doOtherStuff();
// doSomeMoreStuff();
// doSoMuchStuff();

Good:

doStuff();

INTRO TO CLEAN CODE IN JS

Don't have journal comments.

Bad:

/**
 * 2016-12-20: Removed monads, didn't understand them (RM)
 * 2016-10-01: Improved using special monads (JP)
 * 2016-02-03: Removed type-checking (LI)
 * 2015-03-14: Added combine with type-checking (JR)
 */
function combine(a, b) {
  return a + b;
}

Good:

function combine(a, b) {
  return a + b;
}

INTRO TO CLEAN CODE IN JS

Avoid positional markers

Bad:

///////////////////////////////////////
// Scope Model Instantiation
///////////////////////////////////////
$scope.model = {
  menu: 'foo',
  nav: 'bar'
};

///////////////////////////////////////
// Action setup
///////////////////////////////////////
const actions = function() {
  // ...
};

Good:

$scope.model = {
  menu: 'foo',
  nav: 'bar'
};

const actions = function() {
  // ...
};

INTRO TO CLEAN CODE IN JS