# Prevent SUBMIT

**URL:** <https://forums.knack.com/t/prevent-submit/10593>\
**Category:** Get Answers\
**Created:** [July 14, 2021, 10:17am UTC](https://forums.knack.com/t/prevent-submit/10593 "2021-07-14T10:17:28Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![JoeWilliam41025](https://avatars.discourse-cdn.com/v4/letter/j/3e96dc/32.png) [@JoeWilliam41025](https://forums.knack.com/u/JoeWilliam41025)\
**Post date:** [July 14, 2021, 10:17am UTC](https://forums.knack.com/t/prevent-submit/10593/1 "2021-07-14T10:17:28Z")

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Hello, Possible to disable the SUBMIT button if an equation field on an add form is not equal to ZERO? I tried to do this within the app but the values don't technically "exist" at the time you hit SUBMIT so it won't work with any of the rules that I can find.&nbsp;

I don't have much experience with coding but I understand this may be a solution to this problem.

&nbsp;

Thank you all

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**Author:** ![Cheyenne14341](https://avatars.discourse-cdn.com/v4/letter/c/aca169/32.png) [@Cheyenne14341](https://forums.knack.com/u/Cheyenne14341)\
**Post date:** [July 14, 2021, 9:16pm UTC](https://forums.knack.com/t/prevent-submit/10593/2 "2021-07-14T21:16:53Z")

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Since you're dealing with an equation, I think you will have to use some code. To start, I would suggest taking a look at the [custom form validation example code](https://docs.knack.com/docs/javascript-jquery-examples#custom-form-validation)&nbsp;from the Developer Docs.