TYPESCRIPT-BASICS5 MIN READ
Walk a form-state union
Choose discriminated union steps for a UI state that currently uses conflicting booleans.
decision trail state chips before-after panel The bug The form can show loading and success together because the model allows that combination. The UI needs one current state, not three independent flags. Discriminated union One tag, valid data per case A discriminant property lets TypeScript narrow the union and lets product logic express impossible states as impossible. Boolean pile Many combinations, some invalid The compiler follows the same state map as the UI. The tag is the proof. 01 Name states 02 Attach data 03
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