In TypeScript, the "OR" symbol is represented by |. It is used to define a variable as having either one type or another type. Here's an example:
let myValue: string | number;
myValue = 'Hello'; // Valid
myValue = 100; // Valid
myValue = false; // Invalid
In the above example, myValue is defined as having either a string or a number as its value. It cannot have any other value.
The | operator can also be used with interfaces to create a type that includes a combination of types. Here's an example:
interface Car {
make: string;
model: string;
}
interface Motorcycle {
make: string;
model: string;
engineSize: number;
}
type Vehicle = Car | Motorcycle;
const car: Vehicle = {
make: 'Toyota',
model: 'Corolla'
};
const motorcycle: Vehicle = {
make: 'Harley-Davidson',
model: 'Sportster 1200',
engineSize: 1200
};
In the above example, the Vehicle type is defined as either a Car or a Motorcycle. The car variable only has the make and model properties, while the motorcycle variable has those properties as well as an engineSize property.