Union and Literal Types
A union A | B allows either type. A literal type allows one exact value. Together they model choices precisely.
Exampletypescript
Only the listed values are allowed, so typos are caught immediately.
Exampletypescript
Quick check
What does `type Size = "S" | "M" | "L"` allow?
Your turn: write the code
Define type Switch = "on" | "off" and a function flip(s: Switch): Switch that returns the opposite value. Print flip("on").
Finish the quick check (and any code exercise) to complete this lesson, or mark it done yourself.
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