CoffeeScript function 调用-参数和括号

Question

Exists such a Javascript code:

var re = /some_regex/g;
return re.exec(link.attr('href'))[0]

How to call this in CoffeeScript In CoffeeScript there is no need in brackets for parameters but there is another call of function in param.

I've tried:

re = /some_regex/g
re.exec link.attr 'href' [0]   # compile error: unexpected [
re.exec (link.attr 'href')[0]  # javascript: re.exec((link.attr('href'))[0]);
re.exec (link.attr('href'))[0] # javascript: re.exec((link.attr('href'))[0]);

how to do this? or I should make

// adding new variable
temp = re.exec link.attr 'href'
temp[0]

Answer 1

The space after re.exec is causing a problem, because it causes the CoffeeScript compiler to think that (link.attr('href'))[0] is the argument.

The correct way to do this is to do it exactly like in JavaScript, with no space:

re.exec(link.attr('href'))[0]

If you really badly want to use the no-parens syntax on this line, this would also work:

re.exec(link.attr 'href')[0]

(They compile to the same result)

Answer 2

Wouldn't this be clearer if you simply parenthesized the part that absolutely needs it, and do the rest in the most CoffeeScript-like-way?

(re.exec link.attr 'href')[0]

or maybe even (if 'href' is just another attribute):

(re.exec link.attr.href)[0]

or, better, yet, to be more clear, along the lines of what you suggested originally:

matches = re.exec link.attr.href
matches[0] // idiomatic to re.exec: first element is matched RE