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Constraints 0:50
A 50-second explainer of Constraints, narrated over the same demo you can try yourself.
Try the interactive Constraints demo
What this video covers
Constraints are limits the design builds in to rule out the wrong actions, so the easy path is the correct one. Instead of telling people what to do and hoping, you remove the ability to do the wrong thing - a connector that only fits one way, a field that won't accept letters, a "submit" that stays disabled until the form is valid - so whole classes of error simply can't happen.
Free text invites every typo, format and impossible date you can imagine - then you police it with error messages. Constrain the input instead and the bad states never arise: you can't pick a day that doesn't exist, can't type a letter into a number, can't submit until it's valid. The error isn't caught - it's designed out.
