Google JavaScript Style Guide

A tutorialabout Google’s coding standards for source code in the JavaScript programming language. The best stylistic practices for writing clean, understandable code.

Table of Contents

1 Introduction

1.1 Terminology notes

1.2 Guide notes

2 Source file basics

2.1 File name

2.2 File encoding: UTF-8

2.3 Special characters

3 Source file structure

3.1 License or copyright information, if present

3.2 @fileoverview JSDoc, if present

3.3 goog.module statement

3.4 goog.require statements

3.5 The file’s implementation

4 Formatting

4.1 Braces

4.2 Block indentation: +2 spaces

4.3 Statements

4.4 Column limit: 80

4.5 Line-wrapping

4.6 Whitespace

4.7 Grouping parentheses: recommended

4.8 Comments

5 Language features

5.1 Local variable declarations

5.2 Array literals

5.3 Object literals

5.4 Classes

5.5 Functions

5.6 String literals

5.7 Number literals

5.8 Control structures

5.9 this

5.10 Disallowed features

6 Naming

6.1 Rules common to all identifiers

6.2 Rules by identifier type

6.3 Camel case: defined

7 JSDoc

7.1 General form

7.2 Markdown

7.3 JSDoc tags

7.4 Line wrapping

7.5 Top/file-level comments

7.6 Class comments

7.7 Enum and typedef comments

7.8 Method and function comments

7.9 Property comments

7.10 Type annotations

7.11 Visibility annotations

8 Policies

8.1 Issues unspecified by Google Style: Be Consistent!

8.2 Compiler warnings

8.3 Deprecation

8.4 Code not in Google Style

8.5 Local style rules

8.6 Generated code: mostly exempt

9 Appendices

9.1 JSDoc tag reference

9.2 Commonly misunderstood style rules

9.3 Style-related tools

9.4 Exceptions for legacy platforms

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