Style guide for contributors

Thanks for your contribution to Appium! Here are the principles we use when writing javascript. Please conform to these so we can merge your pull request without going back and forth about style. The main principle is: make your code look like the surrounding code.

Linting

All code (except for code in bootstrap.js which uses proprietary Apple methods) must pass JSLint. To check your code, you can simply run grunt lint from the Appium repo dir. If you've created a new .js file, please make sure it is covered by the wildcards in grunt.js or that it is added specifically.

It's easy to have your code linted as you type, which makes the whole process much smoother. We like jshint, which has integrations with a lot of source code editors. The file .jshintrc is checked into the repo, and its contents are:

{
  "laxcomma": true,
  "strict": true,
  "undef": true,
  "unused": true,
  "trailing": true,
  "node": true,
  "es5": true
}

These defined what we want to see warnings about, etc..., while we're editing. See this page for the list of editors and platforms and how to get your editor set up with automatic linting.

Style notes

• Use two spaces for indentation, no tabs
• Use single spaces around operators js var x = 1; not js var x=1;
• Spaces after commas and colons in lists, objects, function calls, etc... js var x = myFunc("lol", {foo: bar, baz: boo}); not js var x = myFunc("lol",{foo:bar,baz:boo});
• Always end statements with semicolons
• Comma-first js var x = { foo: 'bar' , baz: 'boo' , wuz: 'foz' };
• Brackets for function, if, etc... go on same line, else gets sandwiched js if (foo === bar) { // do something } else { // do something else }
• Space after if: js if (foo === bar) { not js if(foo === bar) {
• Avoid bracketless if for one-liners: js if (foo === bar) { foo++; } not js if (foo === bar) foo++;
• Use ===, not ==, and !==, not != for no surprises
• Line length shouldn't be longer than 79 characters
• Break up long strings like this: js myFunc("This is a really long string that's longer " + "than 79 characters so I broke it up, woo");
• Comments should line up with code js if (foo === 5) { myFunc(foo); // foo++; } not js if (foo === 5) { myFunc(foo); //foo++; }
• More to come....