Variable passed to Javascript returns NULL when added to Input Value

Question

So, basically I am trying to pass a variable to a piece of javascript code and then in turn set this value as a hidden input value.

<img alt="" src="Image.jpg" style="width:50px" class="thisclass" title="Title" onclick="thisfunction('Text Here')" />

The value clearly passes okay as I am able to process it with a switch command successfully.

function thisfunction(thisvariable) {
    switch(thisvariable) {
        case 'Text Here' :

However, when I try to set the value of a hidden

<input type="hidden" name="ThisInput" value="N/A" />

document.getElementById("ThisInput").value = thisvariable;

I get the following error in the javascript console

Uncaught TypeError: Cannot set property 'value' of null

I have also tried

$('#ThisInput').val(thisvariable);

However this just seems to blank the value.

I don't see id attribute...

Rayon
– Rayon

2015-07-24 10:57:55 +00:00
Commented Jul 24, 2015 at 10:57 — Rayon
– Rayon, Commented Jul 24, 2015 at 10:57

Ben · Accepted Answer · 2015-07-24 10:57:06Z

3

Looking at this part of your code:

<input type="hidden" name="ThisInput" value="N/A" />
document.getElementById("ThisInput").value = thisvariable;

document.getElementByID and $("#...") will find the ID of an element. "ThisInput" is the name - it has no ID set.

This would work:

<input type="hidden" id="ThisInput" value="N/A" />
document.getElementById("ThisInput").value = thisvariable;

Or if you want to keep it as a name attribute, use a jQuery attribute selector:

$("input[name='ThisInput']").val(thisvariable);

answered Jul 24, 2015 at 10:57

Ben

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2 Comments

Chris Harland Over a year ago

Sometimes you stare at something long enough and your brain just turns to mush. Thanks for this, but having added in the id as above the code is now blanking the value as per the jquery attempt.

Ben Over a year ago

Before the jQuery attempt, try putting console.log(thisvariable). What outputs to the console? It could be that thisvariable is in fact blank - try it with a constant, like $(....).val("Test"); and see what happens?

messerbill · Accepted Answer · 2015-07-24 10:57:34Z

0

you try to select the HTML element via ID.

<input type="hidden" id="ThisInput" name="ThisInput" value="N/A" />

use this and it should work

answered Jul 24, 2015 at 10:57

messerbill

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Comments

duellsy · Accepted Answer · 2015-07-24 12:47:44Z

0

Try this:

<input type="hidden" name="ThisInput" id="ThisInput" value="N/A" />

<script>
  $('#ThisInput').attr('value',thisvariable);
</script>

edited Jul 24, 2015 at 12:47

duellsy

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answered Jul 24, 2015 at 11:07

Danilo Pádua

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2 Comments

Danilo Pádua Over a year ago

Try place an id in your input tag: <input type="hidden" name="ThisInput" id="ThisInput" value="N/A" />

Danilo Pádua Over a year ago

Thank You duellsy . Had forgotten the tags <script></script>

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