Brief Video: Rewriting JavaScript into CoffeeScript

Post by jashkenas » Thu, Apr 19, 2012, 2:26 PM UTC

Post by ecto » Thu, Apr 19, 2012, 3:06 PM UTC

Post by [deleted] » Thu, Apr 19, 2012, 3:19 PM UTC

Post by axiak » Thu, Apr 19, 2012, 3:28 PM UTC

jashkenas wrote: post #6

[deleted] wrote: post #5

[deleted]

I'm not sure where you got that idea -- it's not at all true. "or=" is the same as "||=", and means: Assign the variable on the left to the value on the right if the variable is falsy. "?=" means: Assign the variable on the left to the value on the right if the variable does not yet exist (ie. is either "null" or "undefined"). Two different things, both useful.

    if a? then a else 0

    a ?: 0  (if you like groovy)

    a // 0 (if you like perl)

Post by jashkenas » Thu, Apr 19, 2012, 3:31 PM UTC

axiak wrote: post #7

jashkenas wrote: post #6

Earlier quoted context omitted.

I'm not sure where you got that idea -- it's not at all true. "or=" is the same as "||=", and means: Assign the variable on the left to the value on the right if the variable is falsy. "?=" means: Assign the variable on the left to the value on the right if the variable does not yet exist (ie. is either "null" or "undefined"). Two different things, both useful.

Since ?= looks so familiar, any chance of an elvis or defined-or operator in coffeescript? if a? then a else 0 becomes either a ?: 0 (if you like groovy) or a // 0 (if you like perl)

  result = a ? 0

  result?

  result ?= a