This let's you do things like:
fullName = ({first = 'John', last = 'Doe'}) -> "#{first} #{last}"
Note: CoffeeScrits treats `undefined` and `null` the same, and that's true in
the case of destructuring defaults as well, as opposed to ES2015 which only uses
the default value if the target is `undefined`. A similar ES2015 difference
already exists for function parameter defaults. It is important for CoffeeScript
to be consistent with itself.
fullName2 = (first = 'John', last = 'Doe') -> "#{first} #{last}"
assert fullName('Bob', null) is fullName2(first: 'Bob', last: null)
Fixes#1558, #3288 and #4005.
The following is now allowed:
o =
a: 1
b: 2
"#{'c'}": 3
"#{'d'}": 4
e: 5
"#{'f'}": 6
g: 7
It compiles to:
o = (
obj = {
a: 1,
b: 2
},
obj["" + 'c'] = 3,
obj["" + 'd'] = 4,
obj.e = 5,
obj["" + 'f'] = 6,
obj.g = 7,
obj
);
- Closes#3039. Empty interpolations in object keys are now _supposed_ to be
allowed.
- Closes#1131. No need to improve error messages for attempted key
interpolation anymore.
- Implementing this required fixing the following bug: `("" + a): 1` used to
error out on the colon, saying "unexpected colon". But really, it is the
attempted object key that is unexpected. Now the error is on the opening
parenthesis instead.
- However, the above fix broke some error message tests for regexes. The easiest
way to fix this was to make a seemingly unrelated change: The error messages
for unexpected identifiers, numbers, strings and regexes now say for example
'unexpected string' instead of 'unexpected """some #{really long} string"""'.
In other words, the tag _name_ is used instead of the tag _value_.
This was way easier to implement, and is more helpful to the user. Using the
tag value is good for operators, reserved words and the like, but not for
tokens which can contain any text. For example, 'unexpected identifier' is
better than 'unexpected expected' (if a variable called 'expected' was used
erraneously).
- While writing tests for the above point I found a few minor bugs with string
locations which have been fixed.
Any variables generated by CoffeeScript are now made sure to be named to
something not present in the source code being compiled. This way you can no
longer interfere with them, either on purpose or by mistake. (#1500, #1574)
For example, `({a}, _arg) ->` now compiles correctly. (#1574)
As opposed to the somewhat complex implementations discussed in #1500, this
commit takes a very simple approach by saving all used variables names using a
single pass over the token stream. Any generated variables are then made sure
not to exist in that list.
`(@a) -> a` used to be equivalent to `(@a) -> @a`, but now throws a runtime
`ReferenceError` instead (unless `a` exists in an upper scope of course). (#3318)
`(@a) ->` used to compile to `(function(a) { this.a = a; })`. Now it compiles to
`(function(_at_a) { this.a = _at_a; })`. (But you cannot access `_at_a` either,
of course.)
Because of the above, `(@a, a) ->` is now valid; `@a` and `a` are not duplicate
parameters.
Duplicate this-parameters with a reserved word, such as `(@case, @case) ->`,
used to compile but now throws, just like regular duplicate parameters.
"[v] = a ? b" must compile to
v = (typeof a != "undefined" && a !== null ? a : b)[0];
and not to:
v = typeof a != "undefined" && a !== null ? a : b[0];
