How to Write Clean JavaScript code

Any fool can write code that a computer can understand. Good programmers write code that humans can understand.

• Writing clean code is nothing but code easier to read, modify, and refactor for people other than the original programmer.
• The code should be easy to read, whether that reader is the original author of the code or somebody else. There shouldn’t be any doubts and misunderstandings.
• Things such as application flow, the purpose of each function/class/variable/expression, and how different objects collaborate should be clear.
• Writing clean code has the following advantages,

Lower maintenance burden

Code consistency across the team

Improves code readability

Tips for writing clean code

• Use meaningful names for variables, functions, and objects.

// Don't
let a = 'kamesh sethupathi';
let b = 'kamesh.sethupathi@domain.ext';
function printIt() {
    console.log('Name', a);
    console.log('Email', b);
}

// Do
let name = 'kamesh sethupathi';
let email = 'kamesh.sethupathi@domain.ext';
function printUserInfo() {
    console.log('Name', name);
    console.log('Email', email);
}

• Avoid adding unnecessary context. Like user.userID, image.isValidImage(). It can be simplified like user.ID, image.isValid().
• Never hardcode any values. Always use constants for that purpose.

// Don't
setInterval(pingServer, 10 * 1000);

// Do
const SERVER_PING_INTERVAL = 10 * 1000; // const file
setInterval(pingServer, SERVER_PING_INTERVAL);

• Use default values for arguments

// Don't
function printAllFilesInDirectory(dir) {
  const directory = dir || "./";
  //   ...
}

// Do
function printAllFilesInDirectory(dir = "./") {
  // ...
}

• Only comment business logic
• Favor object literals or maps over switch statements / If-else ladder.

// Don't
if(user == 'admin') {
    console.log('You have full potential');
} else if( user == 'editor') {
    console.log('You can publish, review, and access the page');
}  else if( user == 'author') {
    console.log('You can publish and access the page');
}

// Do
let permissions = {
    admin: 'You have full potential',
    editor: 'You can publish, review, and access the page',
    author: 'You can publish and access the page'
};
console.log( permissions[user] );

• Use shorthands whenever possible
• Use non-negative conditionals. Like prefer isValidUser over isNotValidUser().
• Do not repeat yourself ( DRY )

// Don't
function addTwoNumbers(a, b) {
    console.log(a + b);
}
function addThreeNumbers(a, b, c) {
    console.log(a + b + c);
}

// Do
function addNumbers(...args) {
    console.log( args.reduce((prev, cur)=> prev+cur,0) );
}

• Avoid using flags as arguments. Like having isPublished as an argument.
• Avoid executing multiple actions in a function. A function should do one action that is intended for.

Linkedin: https://www.linkedin.com/in/kameshsethupathi