Javascript Coding Style

Linter setup in VSCode

1. Install Node.js.
2. Install ESLint with npm install -g eslint.
3. Install ESlint extension in VSCode.
4. Configure ESLint in VSCode to set options (format on save, etc.).

#CS400 → #CS499 Javascript

#CS400 Use the w3school JS convention

Use the w3school JS convention where not specified otherwise by our coding style.

#CS401 Use 2 spaces indentation

To be consistent with our C/C++ coding style, we must use 2 spaces (instead of 4) to indent code.

#CS402 Don't use unneeded curly brackets

To be consistent with our C/C++ coding style, don't use curly brackets when not needed (e.g., for single instruction blocks).

#CS403 Check for undefined variable

Use the following syntax to check for an undefined variable:

typeof data === 'undefined'

#CS404 Naming of private variables and functions

The names of private variables and functions must begin with a _.

#CS405 Use ES6 features

Use ES6 features in the code. For example:

• OOP-style class instead of prototypes
• arrow functions
• constants
• blocked scoped variables
• let and const instead of var

#CS406 Use ESLint linter (atom package: linter-eslint)

All the errors reported by ESLint based on the https://github.com/cyberbotics/webots/blob/master/.eslintrc.json configuration file should be fixed. Warnings may be accepted.

#CS407 Don't exceed 128 character for line of code

Line size is limited to 128 characters (instead of 80 in w3school).

#CS408 Private fields

The # prefix should be used to declare private fields or methods:

class ClassWithPrivate {
  #privateField;
  #privateFieldWithInitializer = 42;
  constructor(value) {
   this.#privateField = value;
  }

  #privateMethod() {
    // …
  }

  static #privateStaticField;
  static #privateStaticFieldWithInitializer = 42;

  static #privateStaticMethod() {
    // …
  }
}

Note: such values are not inherited by child classes.

#CS409 Protected fields

Protected attributes and methods should be prefixed with a _.

Note: This is only informative and not actually enforced by JavaScript.