Mastering Union and Intersection Types in TypeScript: Quick Guide with Examples

Union Types: Use union types when a variable or parameter can hold values of multiple types. Syntax: typeA | typeB Example: let value : string | number ; value = " hello " ; // valid value = 42 ; // valid value = true ; // invalid Intersection Types: Use intersection types to combine multiple types into one. The resulting type has all properties from each type. Syntax: typeA & typeB Example: type A = { a : number }; type B = { b : string }; let obj : A & B = { a : 1 , b : " hello " }; Key Differences: Union ( | ) : Accepts values that match any member type. Intersection ( & ) : Requires values to satisfy all member types. Practical Example: Suppose you have user types: type Admin = { name : string ; admin : true }; type User = { name : string ; admin ?: false }; type AnyUser = Admin | User ; // Can be either Admin or User function greet ( user : AnyUser ) { console . log ( `Hello, ${ user . name } ` ); } When to Use Them: Use unions when data can be of different shapes. Use intersectio