JavaScript if condition not working

Question

I am screwed with this one the if statement is not working in javascript. I am using js to call php and php file echo 'true';

My java script code

 function like_add(article_id){
$.post('my/like.php', {article_id:article_id}, function(data){
    if(data == 'true'){//this part never works
        alert(data);
    }else{
    alert(data);
    }
});

}

I tried to change alert with alert('*'+data+'*');

And got that there is a space * true*. How can I get this script t work.

Whole code

 function like_add(article_id){
$.post('ajax/like.php', {article_id:article_id}, function(data){

    if(data == 'true'){
        total_votes(article_id);
    }else{
    alert(data);
    }
});

} PHP code

        if(previously_liked($article_id) === true){
        echo 'You\'ve already liked this!';                 
        }else{
            add_like($article_id);
            echo 'true';
        }


function total_votes(article_id){
$.post('ajax/total_votes.php', {article_id:article_id}, function(data){
    $('#article_'+article_id).text(data);

}); }

Wait ... if the PHP code echoes "success", where does the string with "true" in it come from? — Pointy
– Pointy, Commented Jun 24, 2012 at 13:18
Please post your actual code. I've a strong feeling that this is an untested reduced example. And define "not working". Are you saying that neither condition executes? Or is it always the else? — user1106925
– user1106925, Commented Jun 24, 2012 at 13:19
@am not i am the if is not working as there is white space before string which is echoed an I have tried all sort of methods but nothing worked!! else is working fine — Navneet Pandey
– Navneet Pandey, Commented Jun 24, 2012 at 13:29
@NavneetPandey: What happens if you do alert(typeof data) before the if statement. — user1106925
– user1106925, Commented Jun 24, 2012 at 13:32

Pointy · Accepted Answer · 2012-06-24 13:03:36Z

2

Well you could include a space in your test:

  if (data == ' true') { ... }

Or you could look for the pattern "true" in the data:

  if (/true/.test(data)) { ... }

The latter would probably be more resilient, though really it'd be better to have your server return something more structured and less ambiguous.

answered Jun 24, 2012 at 13:03

Pointy

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2 Comments

Pointy Over a year ago

Well you're going to have to provide more detail; the regular expression would definitely work.

David Thomas Over a year ago

Can you console.log(data) before the if, just to be sure that data is what you expect it is?

KooiInc · Accepted Answer · 2012-06-24 13:34:12Z

0

If it's a leading space bugging you, try

if (data.replace(/^\s+|\s+$/,'').toLowerCase() === 'true')

answered Jun 24, 2012 at 13:34

KooiInc

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Comments

Husain · Accepted Answer · 2012-06-24 13:36:34Z

0

I think you can do following:

Check your response that should not contains space. Or
Use data = data.replace(/\s/g, "");

edited Jun 24, 2012 at 13:36

answered Jun 24, 2012 at 13:07

Husain

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5 Comments

Navneet Pandey Over a year ago

I have tried this. in this also if condition is not working but the alert is without space.

Husain Over a year ago

can you try like if(data == true), I mean without single or double qoutes.

Husain Over a year ago

I think your callback function is returning ' true' (true with space). If it return 'true' (without space) then it will work. Hope this help.

Husain Over a year ago

Use data = data.replace(/\s/g, ""); before if condition.

Husain Over a year ago

Debug it in firefox with firebug, if you know how to debug :)

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