javascript - Document.getElementById.value returning Undefined - Stack Overflow

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Following is my HTML code

<div id="dl_address" class="dl-row">
 <div class="dl-col1">
    <span id="dl_addressMarker" class="dl-Marker">*</span>Address:
 </div>
 <div class="dl-col2">
  <input  id="dl_addressMarker" name="p.streetAddress" maxlength="100" size="15"  
                            class="landing-qualpanel-input-standin" type="text" onClick="formOpt(id)" value="Home Address">
 </div>
</div>

And Following is my javascript code

<script language="javascript" type="text/javascript">
function formOpt(x){

    var y=document.getElementById(x).value;
    alert(y);
    }
</script>

I can't understand why i am getting Undefined. Kindly Help. Thanks in advance

Following is my HTML code

<div id="dl_address" class="dl-row">
 <div class="dl-col1">
    <span id="dl_addressMarker" class="dl-Marker">*</span>Address:
 </div>
 <div class="dl-col2">
  <input  id="dl_addressMarker" name="p.streetAddress" maxlength="100" size="15"  
                            class="landing-qualpanel-input-standin" type="text" onClick="formOpt(id)" value="Home Address">
 </div>
</div>

And Following is my javascript code

<script language="javascript" type="text/javascript">
function formOpt(x){

    var y=document.getElementById(x).value;
    alert(y);
    }
</script>

I can't understand why i am getting Undefined. Kindly Help. Thanks in advance

• javascript
• html

Share Improve this question Follow asked Feb 3, 2013 at 11:50 talhaMalik22talhaMalik22 15544 gold badges55 silver badges1313 bronze badges 1

• For starters you have two different elements with the same ID, which one were you expecting getElementById to return? – Ian Roberts Commented Feb 3, 2013 at 11:54

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3 Answers 3

Sorted by: Reset to default 3

That's because you have two elements with the same Id, which isn't allowed in HTML and which makes it impossible for your function to get the input this way.

Change the id of your input and you'll be fine.

You could simplify the code by passing the element and not the id :

HTML :

<input  id="dl_addressMarker2" name="p.streetAddress"
      maxlength="100" size="15"  
      class="landing-qualpanel-input-standin" type="text"
      onClick="formOpt(this)" value="Home Address">

JavaScript :

function formOpt(x){
   var y = x.value;
   alert(y);
}

You have 2 problems. (1) you should call your method like this: formOpt(this) which will pass the current element in. (2) You have repeated DOM ids.

Write is like this:

<script language="javascript" type="text/javascript">
function formOpt(x){
    //x is now the input element. You can fetch its id property.
    var y=document.getElementById(x.id).value;
    // you can do other things with x also.
    alert(y);
    }
</script>
<div id="dl_address" class="dl-row">
 <div class="dl-col1">
    <span id="dl_addressMarker" class="dl-Marker">*</span>Address:
 </div>
 <div class="dl-col2">
 <!-- I renamed the id on the input -->
  <input  id="dl_addressMarker_input" name="p.streetAddress" maxlength="100" 
  size="15"  class="landing-qualpanel-input-standin" 
 <!-- pass this into the function -->
  type="text" onClick="formOpt(this);" value="Home Address">
 </div>
</div>

See working sample: http://jsfiddle/KXCeh/1/

you need to pass the value of id, and you also need to keep the ids unique for each and every element

            <div class="dl-col2">
  <input  id="dl_addressMarker" name="p.streetAddress" maxlength="100" size="15"  
                            class="landing-qualpanel-input-standin" type="text" onClick="formOpt('dl_addressMarker')" value="Home Address">
 </div>

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