Logic & validation, no scripting

Logic in formformform is a set of rules you read like sentences: when this answer is that, do this. Show a follow-up field only when someone picks "other". Skip a whole page when it doesn't apply to them. Send two different audiences down two different paths from the same form.

Rules are evaluated as the visitor types, so the form quietly rearranges itself around their answers. Nobody waits on a field they'll never fill, and you don't end up cleaning irrelevant responses later.

Validation runs in the browser, the moment a field loses focus — not after a full round-trip to the server. Mark a field required and an empty one can't slip through. Set a field's type to email or number and the format is checked for you. For anything more specific, add a pattern: an order ID, a postcode, a phone shape.

• Required fields block submission until they're filled.
• Email and number types validate format automatically.
• Custom patterns match the exact shape you describe.

Each rule carries its own message, so people see plain guidance like "enter a valid email" instead of a generic error.

A long single scroll is the fastest way to lose someone. Break a form into pages and each step asks for a little, shows a progress indicator, and validates before it lets the visitor move on — so they fix one page at a time rather than meeting a wall of errors at the end.

Pages and logic work together: a jump-to-page rule can carry someone straight from page one to the page that fits their answer, skipping the rest. None of it needs code.