jQuery logical operators for flow control instead of using if statement

Question

For some reason I can't get the succinct flow control syntax to work with jQuery. The following throws an error:

$(this).hasClass('expanded') && return

Whereas this longer version works fine:

if ($(this).hasClass('expanded')) { return}

Any ideas why the first one is throwing an error?

Those two lines are very different, and personally I've never seen the first. — Cᴏʀʏ
– Cᴏʀʏ, Commented Oct 24, 2011 at 15:53

jAndy · Accepted Answer · 2011-10-24 15:52:32Z

5

You cannot use the logical AND with the return statement like this. However, I can't see a reason why you would do it like that. You could just return the boolean result directly from a function

return $(this).hasClass('expanded');

answered Oct 24, 2011 at 15:52

jAndy

237k57 gold badges313 silver badges363 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

techjacker Over a year ago

I'm not interested in returning the result I just want the rest of the code in the block not to execute if the condition is true. I tried this and it doesn't work for me but thanks for your answer anyway, I guess I can't use this syntax with return as you say

jAndy Over a year ago

@techjacker: well, either your example is badly choosen or I don't get it. The thing is, every function in ECMAscript returns a value. If not specified, it returns the undefined value. So, Checking for a boolean expresion to either call return or not, does not make any sense.

Nicola Peluchetti · Accepted Answer · 2011-10-24 16:09:13Z

0

I think you could save tipying the {}:

if($(this).hasClass('expanded')) return;

edited Oct 24, 2011 at 16:09

answered Oct 24, 2011 at 15:51

Nicola Peluchetti

77k32 gold badges151 silver badges197 bronze badges

1 Comment

techjacker Over a year ago

thanks that saved a bit of typing, actually it can be made even shorter by removing the semi colon at the end if($(this).hasClass('expanded')) return

Chris Stephens · Accepted Answer · 2014-10-08 13:51:32Z

0

Each part of the boolean logical operator must evaluate to something. return can't do that.

I actually hadn't thought of using it like that before, I would have thought off the top of my head that it would work too.

answered Oct 8, 2014 at 13:51

Chris Stephens

2,1842 gold badges17 silver badges21 bronze badges

Collectives™ on Stack Overflow

jQuery logical operators for flow control instead of using if statement

3 Answers 3

2 Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related