Form field validation can be set using custom JavaScript in Ui On Change.
Default state (before field changes)
- Set with trigger: onBeforeAccountFormView
- Set Using JavaScript
- Set in the action path associated with the trigger
When field changes
- Behavior occurs when the data in the associated field changes
- Set using JavaScript
- Will vary based on the JavaScript use din the form field's Ui on Change property
Setup
JavaScript can be entered under Setup - Forms - Form - Form Fields - Selected Form Field - Ui On Change

Here is an example of JavaScript that might be used in a Form Field's Ui On Change:
if (this.value === '0')
{
document.getElementById('formCellLabel.MVTO.ACCURATE_LETTER').style.visibility = 'visible';
document.getElementById('formCellField.MVTO.ACCURATE_LETTER').style.visibility = 'visible';
}Watch the video below for additional guidance.
