Cannot read property 'value' of null while accessing js variable in javascript

Question

what i Need

i need to pass url variable from html to javascript file.

html code

    <script>
     var p = "{{ page_param.asy_request | replace('&','&')}}";
     p = p.replace(/\&/g, "&");
     p = "{{ DomainDetect() }}/ajax?for=event_listing&ajax=1" + p;

   </script>

 <input type="hidden" name="mobilepage" id="mobilepage" value="'+p+'"/>

Accesing p variable in javascript code

   var mobile=document.getElementById("mobilepage").value;
   console.log(mobile);

Error

Uncaught TypeError: Cannot read property 'value' of null

i need url should be passed from html file to js file.
i have used hidden element for that.
any suggestion are most welcome.

Christos · Accepted Answer · 2015-01-14 11:31:26Z

1

Your html element hasn't id. Hence you can't select using the document.getElementById. If you want to fix this, you have to add this id, like below:

<input type="hidden" name="mobilepage" id="mobilepage" value=""/>

If you don't want to add an id and you want to leave this element as is, the you should use another method for selecting your element, document.getElementByName.

Below I have added a code snippet to see that it works.

alert(document.getElementById("mobilepage").value);

<input type="hidden" name="mobilepage" id="mobilepage" value="3"/>

edited Jan 14, 2015 at 11:31

answered Jan 14, 2015 at 11:08

Christos

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5 Comments

Christos Over a year ago

@user3785613 have you added the id and it didn't?

user2818060 Over a year ago

updated <script> var p = "{{ page_param.asy_request | replace('&','&')}}"; p = p.replace(/\&/g, "&"); p = "{{ DomainDetect() }}/ajax?for=event_listing&ajax=1" + p; console.log(p); </script> <input type="hidden" name="mobilepage" id="mobilepage" value='"+p+"'/>

user2818060 Over a year ago

js file var mobile=document.getElementById("mobilepage").value; console.log(mobile);

Christos Over a year ago

@user3785613 I think that your problem relies on the way you have defined the value.

user2818060 Over a year ago

alert(document.getElementById("mobilepage") return null

Omri Aharon · Accepted Answer · 2015-01-14 11:08:16Z

0

You're trying to get an element by ID, when you should be getting that element by name. Do:

 var mobile=document.getElementByName("mobilepage").value;

Either that, or change the name to be an ID on the HTML element:

<input type="hidden" id="mobilepage" value=""/>

answered Jan 14, 2015 at 11:08

Omri Aharon

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3 Comments

user2818060 Over a year ago

still the same problem Uncaught TypeError: Cannot read property 'value' of null

user2818060 Over a year ago

updated <input type="hidden" name="mobilepage" id="mobilepage" value="'+p+'"/>

Omri Aharon Over a year ago

@user3785613 If it doesn't work then you have a mismatch between your scripts and the DOM elements, because the element is clearly not available, thus returning undefined.

Ankit K · Accepted Answer · 2015-01-14 11:12:14Z

0

Add id attribute to your input.

answered Jan 14, 2015 at 11:12

Ankit K

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