Recently, I stumbled upon this code snippet in TypeScript
images:Array<Object> = [];
I'm curious, what exactly does the "<>" notation signify?
Recently, I stumbled upon this code snippet in TypeScript
images:Array<Object> = [];
I'm curious, what exactly does the "<>" notation signify?
Generics are a way to specify the type of elements in an array.
For example:
let images: Array<Object> = [];
can be written as:
let images: Object[] = [];
However, using Object is very general. You can be more specific:
let strings: Array<string> = [];
let numbers: Array<number> = [];
interface MyInterface {}
class MyClass1 implements MyInterface {}
class MyClass2 implements MyInterface {}
let arr: Array<MyInterface> = [];
arr.push(new MyClass1());
arr.push(new MyClass2());
Generics can also be used when defining interfaces and classes:
interface MyInterface<T> {
value: T;
}
let obj: MyInterface<string> = { value: "string" };
This is a blank array containing objects.
It's simply an alternative method of expressing the following:
imageList: Object[] = [];
Parametric polymorphism is the term for this concept. Here, Array acts as a type constructor with Object being the argument. The symbols <> are used to represent type arguments for type constructors, similar to how () denote value arguments for functions.
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