CoffeeScript

CoffeeScript is our preferred scripting language for the Rails conversion.^* You should make an attempt use CoffeeScript, though some vendor-specific code may be difficult and confusing to integrate and Javascript may be easier and more readable. If you’re using Javascript, please leave a brief block-comment note at the top of the file with the reason for using JS. This will allow us to go back at a later time and understand why a decision was made.

Style

• Use camelCase with a leading lowercase for variables, methods, and object properties.
• Use CamelCase with a leading uppercase for classes.
• Use SCREAMING_SNAKE_CASE for constants.
• Denote “private” methods and variables with a leading underscore.
• Prefer lines under 80 characters. Keep all lines under 100.
• Do not use trailing semicolons.
• Do not leave trailing whitespace.

Functions

• When declaring functions, use a single space after the closing parentheses of the argument list.

  my_method = (arg1, arg2) -> # good
  my_method = (arg1, arg2)-> # bad

• When chaining method calls and the code doesn’t fit on one line, EVERY call should be on a separate line and indented one level:

  [1..3]
    .map((x) -> x * x)
    .concat([10..12])
    .filter((x) -> x < 11)

• Choose to omit or include parentheses when calling functions in a way that optimizes readability.

Other

• Favor unless over if for negative conditions.
• Do not use else with unless. Rewrite to if..else.
• Prefer string interpolation over concatenation.

^*As time has gone on, this is not necessarily true. Consistency is key – use your best judgment. (Feb 2018)