I can get the vscode tip with number:

but when union with string failed:

CodePudding user response：

The canonical way to do this is to intersect string with {}. string normally would absorb string literal types in a union (the string literal types are already part of string so in effect they are redundant for type checking)

type color = 'white' | 'black' | (string & {}); 

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CodePudding user response：

The 'string' type not working as expected in typescript with union types. You should make it 'String' rather than 'string' and it will work I think.

type color = 'white' | 'black' | String;