jquery alert says undefined

Question

Hi, I'm trying to get the alert method to show the value c8 but it just says undefined.

I'm new to html and jquery; it's simple but I just can't see it.

<!DOCTYPE html>
<html>
  <head>
    <script type="text/javascript" src="jquery/jquery-1.7.1.js"></script>
    <script>
      $(document).ready(function(){
        $("button").click(function(){
      //$("#div1").load("hs.php");
      //$("#div1").load("http://127.0.0.1:81/tenHsServer/tenHsServer.aspx?t=ab&f=DeviceStatus&d=A1");
        $("#div1").load("http://127.0.0.1:81/tenHsServer/tenHsServer.aspx?t=ab&f=ToggleDevice&d=c8");
        alert($(this).prev().attr(".class"));
       });
      });
    </script>
  </head>
  <body>
    <div id="div1"><h2>Let jQuery AJAX Change This Text</h2></div>
    <span class='c8'><button>Get External Content</button></span>
  </body>
</html>

Can you put this in jsfiddle? Also, I believe that it's supposed to be attr("class") with no "." (period) — Jay D., Mar 01 '13 at 22:22
@Ohgodwhy initially I thought that was the issue too but it's just the terrible indentation. There is no `.load()` callback here. — Matt Ball, Mar 01 '13 at 22:23

score 1 · Answer 1 · answered Mar 01 '13 at 22:25

1

Because prev() is for sibblings only. your button is child of that div.

You should go:

alert($(this).parent().attr("class"));

answered Mar 01 '13 at 22:25

monxas

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score 1 · Answer 2 · answered Mar 01 '13 at 22:25

The button has no siblings .prev() is used to select the previous sibling, the element you want to target is its parent therefore use .parent() to select it. Also you only prepend the class with a dot (.) when it is part of a selector.

alert($(this).parent().attr("class"));

score 0 · Answer 3 · answered Mar 01 '13 at 22:21

0

You don't need the dot before attribute names:

alert($(this).prev().attr("class"));

answered Mar 01 '13 at 22:21

SeinopSys

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score 0 · Answer 4 · answered Mar 01 '13 at 22:21

0

While in jQuery the . introduces a class selector, in this case you just want an attribute called "class".

Remove the . in .class:

alert($(this).prev().attr("class"));

answered Mar 01 '13 at 22:21

Eric J.

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score 0 · Answer 5 · answered Mar 01 '13 at 22:22

0

You should use .attr("class") instead (without the .)

answered Mar 01 '13 at 22:22

DarkAjax

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jquery alert says undefined

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