Player Code JavaScript Style Guide

We're teaching people JavaScript. Therefore it is important that we have a consistent and clear coding style that is as close to standard JavaScript as possible. Every Artisan should apply this coding standard in her levels to keep the code through all the levels consistent.

Just basically follow the Node style guide, but with these exceptions and additions:

Formatting

• The basic indention is four spaces. Tabs are not to be used at all.
• Try to keep lines to 60 characters or less. (We are working with very narrow code editors sometimes.)
• Use double quotes.
• Single spaces between binary operators, like food < 5.
• No extra spaces in array or object literals, except between object keys and values.

// Bad
var array = [ 1, 2, 3 ];
var object = { x:30, y:30 };

// Good
var array = [1, 2, 3];
var object = {x: 30, y: 30};

Code style

• Always put else on its own line.
• Use index++, not ++index.
• Don't use the ternary operator.
• Capitalize comments like sentences.

Function and variable naming

• Avoid single letter names (x, i, etc.), unless you need to do a for-loop on one line and a longer name won't fit into 60 characters. Be descriptive with your naming.
• Event handler functions should be prefixed with the word on, like onPetSpawn
• Try to declare local variables as near to their use as possible; try to initialize every variable.

// Bad
function foo(x) {
    var a = 5;
    if(x < 5) {
        return x * x;
    }
    return x + a;
}

// Good
function foo(x) {
    if(x < 5) {
        return x * x;
    }
    var a = 5;
    return x + a;
}

Booleans

• Do not compare x == true or x == false. Use x or !x instead.
• Compare objects to null, numbers to 0 or strings to "" if there is chance for confusion.
• Use == and != instead of === and !==.
• Use shortcuts.

// Bad
if (name != '') {
    // ...stuff...
}

// Good
if (name) {
    // ...stuff...
}

// Bad
if (collection.length > 0) {
    // ...stuff...
}

// Good
if (collection.length) {
    // ...stuff...
}

Summary of the Node style guide rules we're using

Formatting

• No trailing whitespace.
• Use semicolons.
• Opening braces go on the same line.
• Declare one variable per var statement.

Naming Conventions

• Use lowerCamelCase for variables, properties and function names.
• Use UpperCamelCase for class names.
• Use UPPERCASE for Constants.

Variables

• Use trailing commas in Object/Array creation.
• Put short declarations on a single line.
• Only quote Object keys when necessary.

Conditionals

• Use descriptive conditions.

Functions

• Write small functions.
• Return early from functions.
• Name your closures.
• No nested closures.

Comments

• Use // for comments, not /* */.