document.images.imageName is null or not an object

[jxyu]

When I run my code,
…
document.images.imageName.src=this.h_image();
…

I got the error message: “document.images.imageName is null or not an object”

but using the alert(this.h_image()), there is ../img/image1.jpg in a alert box.

Why can get this error?

[r51]

Try document.images[imageName].src

[jxyu]

I have tried it, but still getting the error “document.images.imageName is null or not an object”.

[kyberfabrikken]

Then the variable document.images.imageName doesn't exist. Can you show the code in context?

[jxyu]

<img src="../../img/h_030.jpg" name="imageName" Id="imageName" width="470" height="334">

I have tried to use document.images['imageName'].src=this.h_image();
and document.getElementById('imageName').src=this.h_image();
it is still to get same error.

Please help to find which is wrong.

[kyberfabrikken]

Where do you run the javascript code from? (Where is the <script> tag placed)

[r51]

Yes, if your script is running before the image has loaded then your img may not yet be part of the DOM and so imageName may well be null.

To test it, you could put your code inside a function attached to window.onload:

window.onload = function() { /* your code */ };

That way, your image will have loaded before the code runs.

[jxyu]

The document.getElementById('imageName').src call path and file name of

images from constructor. Does you mean to put the constructor or method

into the window.onload = function() { put constructor or method in here? };

I'm confusing.

[jxyu]

I have resolved this problem which is to set the length of Array and Array[o] is not reasonable in the object of the constructor, to cause an error: document.getElementById('imageName').src is null or not an object.

Thank you for your help and suggestion.