Compare String in javascript

Question

In jquery ajax function I recive to the server "true" or "false" strings. Then I only wnat know result but only get false in if condition.

 $.ajax({
    ...
        success: function(result) {
              if(result == "true"){   // false???????
                    alert('true');
                } else {
                    alert('false');
                }
             }
        })
    ...

$.ajax({
...
    success: function(result) {
          var result2 = String(result); 
          alert(result2);          // true
          alert(typeof result2);   // String
          alert(typeof "true");    // String
          if(result2 == "true"){   // false???????
                alert('true');
            } else {
                alert('false');
            }
         }
    })
...

...

Somebody can help me?

If your interpreter says that result == "true" is false then result is not "true". Simple as that. You might want to check if your assumption of what result is, are really holding. Try console.log(result). — Yoshi
– Yoshi, Commented May 2, 2012 at 9:38
you're using jQuery, and jQuery uses "smart guesses" sometimes to figure the result type. try result === true. It might have turned into boolean. — Joseph
– Joseph, Commented May 2, 2012 at 9:40

Dandy · Accepted Answer · 2012-05-02 09:39:21Z

5

There could be line breaks or extra spaces in "result".

answered May 2, 2012 at 9:39

Dandy

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1 Comment

Dani Over a year ago

Prize for you! I only looking for problem in JS, but I was using println() function instead print() to response in java servlet.

mplungjan · Accepted Answer · 2012-05-02 09:44:53Z

0

Hmm,

An empty string, null, 0 and undefined are all false

result2==="true" is a better test

DEMO

edited May 2, 2012 at 9:44

answered May 2, 2012 at 9:36

mplungjan

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Comments

score 0 · Accepted Answer · 2014-07-07 09:23:45Z

0

use trim() function...

e.g:

$.ajax({

...

success: function(result) {
      var result2 = String(result.trim()); 
      alert(result2);          // true
      alert(typeof result2);   // String
      alert(typeof "true");    // String
      if(result2 == "true"){   // true
            alert('true');
        } else {
            alert('false');
        }
     }
})

...

edited Jul 7, 2014 at 9:23

answered Jul 7, 2014 at 9:11

user2481398

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