This is a relatively little known and under-used feature of javascript which can be very useful in guiding a user through a form. Using the disabled tag, you can switch on and off elements in a form.
This is a relatively little known and under-used feature of javascript which can be
very useful in guiding a user through a form. Using the disabled tag, you can switch on
and off elements in a form.
Here is a standard text field:
Now here it is again, disabled:
Try typing in the second box, and you'll see that you can't - it's been disabled.
You can do the same any other elements in a form - checkboxes, selection boxes and the rest.
Disabling Form Elements - Common Uses
One common use of this is to only enable the element, once the appropriate
field has been selected earlier in the form.
Now here's a practical example. The 'explain your choice' field only becomes enabled when I have selected the answer to Question 1.
Before selecting a radio button, try typing in the text field - you can't!
Disabling Form Elements - How it's done
To disable an element, put the phrase disabled="true" within the element tag.
Once you've set the disabled tag, you can enable it using something like the following code:
<script language="/javascript/index.html">
function enableField()
{
document.form1.address2.disabled=false;
}
</script>
<a href="javascript:enableField()">Click here to enable the element<a/>
With disabled set to false, the form element becomes useable.
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