Tag: Js typeof

TypeScript adds a typeof operator you can use in a type context to refer to the type of a variable or property : let s = “hello”; let n : typeof s ; let n: string. This isn’t very useful for basic types, but combined with other type operators, you can use typeof to conveniently express many patterns.

TypeScript adds a typeof operator you can use in a type context to refer to the type of a variable or property : let s = “hello”; let n : typeof s ; let n: string. This isn’t very useful for basic types, but combined with other type operators, you can use typeof to conveniently express many patterns.

typeof is used when you need to distinguish between types number , string , boolean , and symbol . Other string constants will not error, but won’t be used to narrow types either. Unlike instanceof , typeof will work with a variable of any type. In the example below, foo could be typed as number | string without issue.

typeof is used to differentiate between the different types in TypeScript . By the use of typeof we can differentiate between number, string, symbol, Boolean, etc. typeof can be used with any type in TypeScript, by the use of it we can re-use the code by passing any parameter type.

TypeScript has another type called empty type denoted by {} , which is quite similar to the object type.