"IF ELSE" Javascript not working

Question

A) I have a first function which works very well :

  if(onlyUs == '1' && idUser == '0'){
            obj.after(jQuery('<div />').css({'clear':'both'}).addClass('kklike-msg').text('Only registered users can vote.'));
            setTimeout(function(){
                jQuery('.kklike-msg').fadeOut('normal');
            },3000);
            return false;
        }

B) So I thought I could do the following thing :

        if(idUser == '0'){
                if(action == 'like'){
                        var ajaxAction = 'add_like';
                }else{
                        var ajaxAction = 'remove_like';
                }
        }else{
            if(action == 'like'){
                        var ajaxAction = 'add_like';
                        window.open('http://mywebsite.com/like')
                }else{
                        var ajaxAction = 'remove_like';
                        window.open('http://mywebsite.com/remove')
                }
        }

C) Knowing that the original function is simply (works well):

if(action == 'like'){
                        var ajaxAction = 'add_like';
                }else{
                        var ajaxAction = 'remove_like';
                }

But B) is not working. In both condition (Login or not), the new window is going to open. Do you have a solution ?

Login or not, idUser is never '0' ,so the execution will always go straight to the else block. — Teemu
– Teemu, Commented Feb 10, 2013 at 16:10
this code does nothing really: if(action == 'like') { var ajaxAction = 'add_like'; } else { var ajaxAction = 'remove_like'; } as soon as you are out of the if, the declared variables go away — Mark Schultheiss
– Mark Schultheiss, Commented Feb 10, 2013 at 16:49

Community · Accepted Answer · 2017-05-23 12:27:02Z

6

Without knowing the type of idUser, it is difficult to tell what the problem is, but the most likely culprit is the use of == for comparison instead of ===. JavaScript will convert the variables being compared into similar types when using ==, which can cause some very unpredictable results in your case.

I recommend writing your code like the following. If this still does not work as you expected, you should investigate what the value of idUser actually is. It may not be a string which would be the cause of your problem.

if (idUser === '0') {
    if(action === 'like') {
        var ajaxAction = 'add_like';
    } else {
        var ajaxAction = 'remove_like';
    }
} else {
    if (action === 'like') {
        var ajaxAction = 'add_like';
        window.open('http://mywebsite.com/like');
    } else {
        var ajaxAction = 'remove_like';
        window.open('http://mywebsite.com/remove');
    }
}

For a very simple example of why you should use ===, see this blog post:

http://longgoldenears.blogspot.com/2007/09/triple-equals-in-javascript.html

edited May 23, 2017 at 12:27

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answered Feb 10, 2013 at 16:15

Dan Herbert

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1 Comment

Dan Herbert Over a year ago

@Teemu, Which is why it really is important to know what the value of idUser is in this case. There could be code executing before this block setting the value to 1, '1', true, etc. Without the value of idUser, the reason this code is failing is unclear.

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