Why is my JavaScript code functioning properly on jsfiddle but failing to work when run locally?

Question

Why is my JavaScript code functioning properly on jsfiddle but failing to work when run locally?

After recently creating JavaScript code that allows for form submission using the <form> tag, I encountered an issue when trying to implement it within an HTML page. Here is a snippet of the code:

<script type="text/javascript">
var myForm = document.forms['myForm'];

var formSubmit = document.getElementById('formSubmit');


formSubmit.onclick = function(){
myForm.submit();
}
</script>

<form name="myForm" action="http://msn.com" method="post"> 
</form>
<div id="formSubmit"><button>Click me</button></div>

While testing the code on http://jsfiddle.net/HrCxz/, everything worked as expected. However, upon transferring the code to an HTML file and running the page, it failed to work. Can anyone provide insight into what might be causing this issue and help me troubleshoot and correct it? Your assistance is greatly appreciated.

javascript html dom-events

Answer 1

Answer №1

When running your code in the fiddle, it is contained within an onload handler by default. However, you have the option to change this in the left-hand panel. If you switch it to run in the <head>, the fiddle will not function properly: http://jsfiddle.net/HrCxz/1/

To resolve this issue, you must either include your own onload handler or relocate your script block after the elements it is meant to manipulate. Script blocks are executed as the browser parses the page from top to bottom, so JS can only interact with elements that have already been parsed. Unless your code is within an event handler triggered by the onload event (or on document ready for supported browsers or with a library that offers such functionality), it won't be able to manipulate elements later in the source.

Answer 2

When running your code in the fiddle, it is contained within an onload handler by default. However, you have the option to change this in the left-hand panel. If you switch it to run in the <head>, the fiddle will not function properly: http://jsfiddle.net/HrCxz/1/

To resolve this issue, you must either include your own onload handler or relocate your script block after the elements it is meant to manipulate. Script blocks are executed as the browser parses the page from top to bottom, so JS can only interact with elements that have already been parsed. Unless your code is within an event handler triggered by the onload event (or on document ready for supported browsers or with a library that offers such functionality), it won't be able to manipulate elements later in the source.

Answer 3

Answer №2

JSFiddle is making use of the onload event.

Step 1:

Test this out by ensuring your JavaScript code is placed after the closing <form> tag,

<form name="myForm" action="http://msn.com" method="post"> 
</form>
<div id="formSubmit"><button>Click me</button></div>

<script type="text/javascript">
   var myForm = document.forms['myForm'];

   var formSubmit = document.getElementById('formSubmit');


   formSubmit.onclick = function(){
      myForm.submit();
   }
</script>

Step 2:

Alternatively, you can add the onload event in this manner,

<script type='text/javascript'>//<![CDATA[ 
  window.addEvent('load', function() {
     var myForm = document.forms['myForm'];

     var formSubmit = document.getElementById('formSubmit');

     formSubmit.onclick = function(){
         myForm.submit();
     }
  });//]]>  

</script>

<form name="myForm" action="http://msn.com" method="post">
</form>

<div id="formSubmit"><button>Click me</button></div>

Answer 4

JSFiddle is making use of the onload event.

Step 1:

Test this out by ensuring your JavaScript code is placed after the closing <form> tag,

<form name="myForm" action="http://msn.com" method="post"> 
</form>
<div id="formSubmit"><button>Click me</button></div>

<script type="text/javascript">
   var myForm = document.forms['myForm'];

   var formSubmit = document.getElementById('formSubmit');


   formSubmit.onclick = function(){
      myForm.submit();
   }
</script>

Step 2:

Alternatively, you can add the onload event in this manner,

<script type='text/javascript'>//<![CDATA[ 
  window.addEvent('load', function() {
     var myForm = document.forms['myForm'];

     var formSubmit = document.getElementById('formSubmit');

     formSubmit.onclick = function(){
         myForm.submit();
     }
  });//]]>  

</script>

<form name="myForm" action="http://msn.com" method="post">
</form>

<div id="formSubmit"><button>Click me</button></div>

Answer 5

Answer №3

It appears that you are triggering the click event on a div element, but perhaps this action should be performed on a button instead? Consider selecting the button using the following code:

var formSubmit = document.getElementById('BUTTONIDHERE');

Answer 6

It appears that you are triggering the click event on a div element, but perhaps this action should be performed on a button instead? Consider selecting the button using the following code:

var formSubmit = document.getElementById('BUTTONIDHERE');

Answer 7

Answer №4

It seems that your code sample isn't working because the JavaScript is being processed before the browser has finished loading the DOM elements. To fix this, you can either move your JavaScript snippet just before the closing body tag so it's executed after the DOM loads, or use an 'on load' or 'on ready' event handler to ensure your JavaScript fires after the DOM is fully loaded.

Below are three examples of how you can execute your JavaScript once the DOM elements have loaded:

1) If you're using jQuery, place your JavaScript inside the $(document).ready() event handler:

$(document).ready(function() {
  // Code within .ready() function
  var myForm = document.forms['myForm'];
  var formSubmit = document.getElementById('formSubmit');

  formSubmit.onclick = function(){
    myForm.submit();
  }
});

2) Another way with jQuery is to utilize the alternate syntax for document 'ready':

$(function() {
  // Code within .ready() function
  var myForm = document.forms['myForm'];
  var formSubmit = document.getElementById('formSubmit');

  formSubmit.onclick = function(){
    myForm.submit();
  }
});

3) You can also bind your JavaScript to a callback function triggered by the window 'load' event - another way to handle post-DOM-loading actions:

window.addEvent('load', function() {
  var myForm = document.forms['myForm'];
   var formSubmit = document.getElementById('formSubmit');

   formSubmit.onclick = function(){
     myForm.submit();
   }
})

Cheers!

Answer 8

It seems that your code sample isn't working because the JavaScript is being processed before the browser has finished loading the DOM elements. To fix this, you can either move your JavaScript snippet just before the closing body tag so it's executed after the DOM loads, or use an 'on load' or 'on ready' event handler to ensure your JavaScript fires after the DOM is fully loaded.

Below are three examples of how you can execute your JavaScript once the DOM elements have loaded:

1) If you're using jQuery, place your JavaScript inside the $(document).ready() event handler:

$(document).ready(function() {
  // Code within .ready() function
  var myForm = document.forms['myForm'];
  var formSubmit = document.getElementById('formSubmit');

  formSubmit.onclick = function(){
    myForm.submit();
  }
});

2) Another way with jQuery is to utilize the alternate syntax for document 'ready':

$(function() {
  // Code within .ready() function
  var myForm = document.forms['myForm'];
  var formSubmit = document.getElementById('formSubmit');

  formSubmit.onclick = function(){
    myForm.submit();
  }
});

3) You can also bind your JavaScript to a callback function triggered by the window 'load' event - another way to handle post-DOM-loading actions:

window.addEvent('load', function() {
  var myForm = document.forms['myForm'];
   var formSubmit = document.getElementById('formSubmit');

   formSubmit.onclick = function(){
     myForm.submit();
   }
})

Cheers!

Why is my JavaScript code functioning properly on jsfiddle but failing to work when run locally?

Answer №1

Answer №2

Answer №3

Answer №4

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