# Prevent form submit via javascript **URL:** \ **Category:** Get Answers\ **Created:** [September 6, 2016, 4:20am UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138 "2016-09-06T04:20:52Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Markus91352](https://avatars.discourse-cdn.com/v4/letter/m/3d9bf3/32.png) [@Markus91352](https://forums.knack.com/u/Markus91352)\ **Post date:** [September 6, 2016, 4:20am UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138/1 "2016-09-06T04:20:52Z")
I have a two fields where the user is required to fill only one of them, while the other can be blank. He can also fill both, doesn't matter. This can not be done with Knack itself (or I don't know how) so I have to resort to a simple custom javascript validation. If both fields are empty, I show an error message and stop the form submitting. And here is my problem. How can I prevent Knack from submitting the form manually? If I listen to the submit event and do a 'return false', it doesn't work. Since I can not see an action url in the form element, I am thinking Knack has it's own form submit logic. How can I capture that and stop it from submitting the form? Thank you! ---
**Author:** ![CarolPinil06400](https://avatars.discourse-cdn.com/v4/letter/c/db5fbb/32.png) [@CarolPinil06400](https://forums.knack.com/u/CarolPinil06400)\ **Post date:** [January 11, 2018, 4:20pm UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138/2 "2018-01-11T16:20:12Z")
``` Hola, estoy interesado en ingresar la documentación pero no puedo iniciar sesión para ver, habrá una forma de obtener la documentación desde otro lado o por favor díganme cuál fue la solución que encontró ``` ---
**Author:** ![CarolPinil06400](https://avatars.discourse-cdn.com/v4/letter/c/db5fbb/32.png) [@CarolPinil06400](https://forums.knack.com/u/CarolPinil06400)\ **Post date:** [January 11, 2018, 4:19pm UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138/3 "2018-01-11T16:19:18Z")
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**Author:** ![CarolPinil06400](https://avatars.discourse-cdn.com/v4/letter/c/db5fbb/32.png) [@CarolPinil06400](https://forums.knack.com/u/CarolPinil06400)\ **Post date:** [January 11, 2018, 4:17pm UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138/4 "2018-01-11T16:17:03Z")
* * * Detectar idioma Afrikáans Albanés Alemán Amárico Árabe Armenio Azerbaiyano Bengalí Bielorruso Birmano Bosnio Búlgaro Canarés Catalán Cebuano Checo Chino (Simplificado) Chino (Tradicional) Cingalés Coreano Corso Criollo haitiano Croata Danés Eslovaco Esloveno Español Esperanto Estonio Euskera Finés Francés Frisón occidental Gaélico escocés Galés Gallego Georgiano Griego Guyaratí Hausa Hawaiano Hebreo Hindi Hmong Húngaro Igbo Indonesio Inglés Irlandés Islandés Italiano Japonés Javanés Jemer Kazajo Kirguís Kurdo Lao Latín Letón Lituano Luxemburgués Macedonio Malayalam Malayo Malgache Maltés Maorí Maratí Mongol Neerlandés Nepalí Noruego Nyanja Panyabí Pastún Persa Polaco Portugués Rumano Ruso Samoano Serbio Sesotho meridional Shona Sindhi Somalí Suajili Sueco Sundanés Tagalo Tailandés Tamil Tayiko Telugu Turco Ucraniano Urdu Uzbeko Vietnamita Xhosa Yidis Yoruba Zulú Español     ``` Hola, estoy interesado en ingresar la documentación pero no puedo iniciar sesión para ver, habrá una forma de obtener la documentación desde otro lado o por favor díganme cuál fue la solución que encontró ``` ---
**Author:** ![Markus91352](https://avatars.discourse-cdn.com/v4/letter/m/3d9bf3/32.png) [@Markus91352](https://forums.knack.com/u/Markus91352)\ **Post date:** [September 9, 2016, 8:15am UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138/5 "2016-09-09T08:15:28Z")
Thank you Brad, I don't know how I missed that, I was searching around a lot for custom validation, since I thought this isn't a too exotic request. Still didn't find that :/ In my tries I was listening to the form submit event. Apparently Knack is listening on the click event for the submit button. That's probably why my 'return false' didn't do anything, since it had no effect on the click event. It is working now with the code provided in the example. I am very happy, thank you very much!! ---
**Author:** ![BradStevens](https://sea2.discourse-cdn.com/flex020/user_avatar/forums.knack.com/bradstevens/32/140_2.png) [@BradStevens](https://forums.knack.com/u/BradStevens)\ **Post date:** [September 8, 2016, 8:46pm UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138/6 "2016-09-08T20:46:58Z")
Markus - check out the documentation for javascript code examples and this custom validation snippet: [http://helpdesk.knackhq.com/support/solutions/articles/5000447560-javascript-code-examples#jqcustomvalidate](http://helpdesk.knackhq.com/support/solutions/articles/5000447560-javascript-code-examples#jqcustomvalidate) ---
**Author:** ![Markus91352](https://avatars.discourse-cdn.com/v4/letter/m/3d9bf3/32.png) [@Markus91352](https://forums.knack.com/u/Markus91352)\ **Post date:** [September 7, 2016, 8:37am UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138/7 "2016-09-07T08:37:41Z")
Thank you very much, this is close enough and should work just fine, thanks! Coming back to the original question though, is it possible to intercept the knack form submission? For example validating a name field does not work this way, because inside knack, the name is one field and I can not select first and last name separately. We want to send the data to zapier and to another app which chokes on missing first or last names since they are required there. Knack however does accept only first name or only last name. Do you have any idea about that? ---
**Author:** ![StevanLECO51061](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@StevanLECO51061](https://forums.knack.com/u/StevanLECO51061)\ **Post date:** [September 7, 2016, 8:19am UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138/8 "2016-09-07T08:19:28Z")
Then you can set validation rule in your DB object Just select either one of the 2 fields and set validation rule :  When "field 1" "is blank" When "field 2" "is blank" Show message : "please fill at least 1 field" ---
**Author:** ![Markus91352](https://avatars.discourse-cdn.com/v4/letter/m/3d9bf3/32.png) [@Markus91352](https://forums.knack.com/u/Markus91352)\ **Post date:** [September 7, 2016, 7:42am UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138/9 "2016-09-07T07:42:20Z")
Thank you for your reply, my scenario is, that ONE of both are required, not both. In Data I can either set both to required or none or just one but that doesn't solve the problem. I need to do custom validation (another thing is that the name field gets validated by knack if only first or last name is filled, so there it is the exact opposite) in order to accept the form if only one of the two fields are filled, but reject it, if none of them are filled. ---
**Author:** ![StevanLECO51061](https://avatars.discourse-cdn.com/v4/letter/s/e47c2d/32.png) [@StevanLECO51061](https://forums.knack.com/u/StevanLECO51061)\ **Post date:** [September 7, 2016, 7:23am UTC](https://forums.knack.com/t/prevent-form-submit-via-javascript/10138/10 "2016-09-07T07:23:40Z")
Hi. In data \> object, you can set the required field option \> settings as "required". I think it will solve your pb