can anyone tell me how this syntax is called and what it does?

Question

I was reading through Ionic's source and stumbled on this part here.

fromTemplateUrl: function(url, options, _) {
  var cb;
  //Deprecated: allow a callback as second parameter. Now we return a promise.
  if (angular.isFunction(options)) {
    cb = options;
    options = _;
  }
  return $ionicTemplateLoader.load(url).then(function(templateString) {
    var modal = createModal(templateString, options || {});
    cb && cb(modal);
    return modal;
  });
}

What's the syntax in line 10 , "cb && cb(modal);" , called and what does it do?

The conditional && is confusing me

[On && and || in Javascript](http://www.grauw.nl/blog/entry/510) — bansi, Jul 18 '14 at 09:59
that makes sense, is there a name for this kind of shortcut? — AdrianLoer, Jul 18 '14 at 10:00

score 3 · Answer 1 · edited May 23 '17 at 10:33

3

thanks everyone, the answer by jon, a shorter way for

if(cb) cb(modal)

combined with the explanation at Assignment with double ampersand "&&" answer my question

I'll remember this as "short if exists syntax"

edited May 23 '17 at 10:33

Community

1
1

answered Jul 18 '14 at 10:07

AdrianLoer

624
3
11

score 2 · Accepted Answer · answered Jul 18 '14 at 10:08

2

undefined && 42 // undefined, the second part wouldn't be evaluated
'defined' && 42 // 42
undefined || 42 // 42
'defined' || 42 // 'defined', the second part wouldn't be evaluated

That way this thing is working.

answered Jul 18 '14 at 10:08

Unrealsolver

143
4

can anyone tell me how this syntax is called and what it does?

2 Answers2