class - nberlette/is GitHub Wiki

@nick/is/class

isClass

Signature

function isClass<
  T,
  A extends readonly unknown[] = readonly any[],
  P extends object | null = Is<T, object | null>,
>(it: unknown): it is Class<T, A, P>;

Checks if a given value is a constructor function, also known as a class.

This includes all pure functions - no generators, arrow functions, or getters/setters - that also have an own prototype propertty which is a non-null object. The prototype must have an own constructor property that points back to the class constructor function itself. Lastly, the function's source code is inspected for the class keyword, to ensure that it is a class and not just a regular function.

Parameters
Name Info
it The value to check.
Returns

true if the value is a class, false otherwise.

Category

Objects

Examples

import { isClass } from "jsr:@nick/is/class";

class Foo {}
console.log(isClass(Foo)); // true

const Bar = function () {
  this.foo = "bar";
  return this;
};
console.log(isClass(Bar)); // false

const Baz = () => {};
console.log(isClass(Baz)); // false

Class

Category

Types

Examples

import { isClass } from "jsr:@nick/is/class";

class Foo {}
console.log(isClass(Foo)); // true

const Bar = function () {
  this.foo = "bar";
  return this;
};
console.log(isClass(Bar)); // false

const Baz = () => {};
console.log(isClass(Baz)); // false
Type Parameters
  • T (default: any)
  • A extends readonly unknown[] (default: readonly any[])
  • P extends object | null (default: Is<T, object | null>)

Properties

prototype

readonly prototype: P;
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