Standard JS - The Rules

• 2 spaces - for indentation

• Single quotes for strings - except to avoid escaping

• No unused variables - this one catches tons of bugs!

• No semicolons - It's fine. Really!​

• Never start a line with (,[, or ` !

  • This is the only gotcha with omitting semicolons - they are automatically checked for you!

  • ​More details​

• Space after keywords: if (condition) {...}

• Space after function name: function name (arg) { ... }

• Always use === instead of ==

  • The use of obj == null is allowed to check for null || undefined

• Always handle the node.js err function parameter

• Always prefix browser globals with window

  • Except for document and navigator, which are okay.

    • This prevents accidental use of poorly-named browser globals like open, length, event, and name.

• And more goodness – give standard a try today!

To get a better idea, take a look at a sample file written in JavaScript Standard Style. Or, check out one of the thousands of projects that use standard!

Courtesy of StandardJS.com</cite>

JavaScript Style Recommendations from Meteor​

An example of refactoring from JavaScript to ES2015

Use the ecmascript package

ECMAScript, the language standard on which every browser’s JavaScript implementation is based, has moved to yearly standards releases... Meteor’s ecmascript package compiles this standard down to regular JavaScript that all browsers can understand using the popular Babel compiler. It’s fully backwards compatible to “regular” JavaScript, so you don’t have to use any new features if you don’t want to. We’ve put a lot of effort into making advanced browser features like source maps work great with this package, so that you can debug your code using your favorite developer tools without having to see any of the compiled output.

The ecmascript package is included in all new apps and packages by default, and compiles all files with the .js file extension automatically. See the list of all ES2015 features supported by the ecmascript package.

To get the full experience, you should also use the es5-shim package which is included in all new apps by default. This means you can rely on runtime features like Array#forEach without worrying about which browsers support them.

Follow a JavaScript style guide

We recommend choosing and sticking to a JavaScript style guide and enforcing it with tools.