Sometimes, we want to extend an array in TypeScript.
In this article, we’ll look at how to extend an array in TypeScript.
How to extend an array in TypeScript?
To extend an array in TypeScript, we can add the method to Array.prototype and add the method to the Array interface.
For instance, we write
interface Array<T> {
remove(o: T): Array<T>;
}
Array.prototype.remove = function (o) {
// ...
return this;
};
to add the remove method to the Array<T> interface.
Then we set Array.prototype.remove to a method that removes the entry from the current array, which is the value of this.
Then we return this which is the array without o.
If the code is in a module, we also need to add the remove property to the Array interface in a type declaration file.
For instance, in a .d.ts file, we write
declare global {
interface Array<T> {
remove(o: T): Array<T>;
}
}
to add remove to it.
Conclusion
To extend an array in TypeScript, we can add the method to Array.prototype and add the method to the Array interface.
