Javascript: check a form object is exist or not

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February 5th, 2002, 10:51 PM

sunnychan

a lazy guy

Join Date: Aug 2001

Location: Hong Kong

Posts: 99

Time spent in forums: < 1 sec
Reputation Power: 12

Javascript: check a form object is exist or not

Hello,

How do you check a form object is exist or not in javascript?

eg.
in html(A):

<html>
<form name="myForm">
input: <input name="myBox" type="text">
</form>
</html>

in html(B):

<html>
<form name="myForm">
</form>
</html>

In the HTML(B), the input box named 'myBox' is not exist.
How do I check its existence in javascript?

the code belows does not work
if (document.MyForm.myBox)
alert("exist!");

February 5th, 2002, 11:08 PM

mrrichardfeder

Contributing User

Join Date: Nov 2001

Posts: 765

Time spent in forums: 3 m 45 sec
Reputation Power: 12

You get exactly one undefined property without JavaScript throwing an error - so
if (document.MyForm.myBox)
should work fine, so long as there's a MyForm to find. My guess is: you're running that in the <head>er, before the form has been created. There's nothing but a document object at that point so you'll definately get an error when the script engine hits MyForm. Put it in a function & call onload, or stick in a JS block below the form.

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