Be liberal in what you accept and conservative in what you send, which for interfaces means accepting messy input and returning clean output.
Law · Robustness
Tag
validation
Entries tagged validation, drawn from across the library. Tags cut through the section structure, which is where most of the useful connections are.
7 entries across 4 sections
Type
Category
Level
7 entries
Better than a good error message is a design in which the error cannot occur.
Heuristic · Nielsen heuristics
Restricting what is possible is the cheapest way to prevent an entire class of error.
Principle · Interaction
Checking input at the right moment, which is rarely while the user is still typing.
Pattern · Forms
Free-form entry, where the label, the hint and the error placement do most of the work.
Component · Forms
Errors must be identified in text, described specifically, and accompanied by a suggested fix where one is known.
Accessibility · Understandable
A review pass for any form, covering structure, labelling, validation, errors and accessibility.
Checklist · Forms