Style Guide

Tim van der Meij edited this page Aug 12, 2015 · 18 revisions

This page outlines the style conventions that PDF.js follows to maintain a consistent codebase. We ask each contributor that creates a pull request to adhere to these conventions. Some of these conventions will also be checked automatically by a linting tool after each push to a branch of a pull request.

General

Naming

  • Variables and functions: lowerCamelCase
  • Constructor-like functions: UpperCamelCase
  • Constants: ALL_UPPER_CASE_WITH_UNDERSCORES

Braces

Always use braces and put them on same line, even for single line control statements:

if (someVar) {
  return true;
} else {
  return null;
}

White space

Keep one space after control statements (if, else, while, for, et cetera):

if (someVar) {

Equalities

Use only strict equalities (===) and inequalities (!==):

if (someVar === conditionA) {
  return true;
} else if (someVar !== conditionB) {
  return false;
}

Variables

Variables must be defined only once within a function scope, preferably at the top of the function.

Classes

The standard way of creating classes in PDF.js is the following. Please note that by class we mean an object that is class-like. Also, note the naming of all anonymous functions.

var ClassName = (function ClassNameClosure() {
  function ClassName(...) {
    ...
  }

  ClassName.prototype = {
    functionName: function ClassName_functionName(...) {
      ...
    },

    aLongFunctionName: function ClassName_aLongFunctionName(arg1,
                                                            arg2,
                                                            ...) {
      ...
    },

    aVeryLongFunctionName: 
        function ClassName_aVeryLongFunctionName(...) {
      ...
    }
  };

  return ClassName;
})();