ts-imm

Simple data classes in TypeScript, modeled after case classes in Scala.

Usage

class SimpleData extends Imm<SimpleData> {
  @imm public name!: string;
  @imm public address?: string;

  public someBusinessLogic(): this {
    return this.copy({name: "new name"});
  }
}

describe("imm", () => {
  it("can create a new instance", () => {
    const d = new SimpleData({name: "a"});
    expect(d.name).toEqual("a");
    expect(d.address).toBeUndefined();
  });

  it("can someBusinessLogic a property with a method", () => {
    const a = new SimpleData({name: "a"});
    expect(a.name).toEqual("a");
    const b = a.someBusinessLogic();
    expect(a.name).toEqual("a");
    expect(b.name).toEqual("new name");
  });

  it("can someBusinessLogic a property with the generic copy constructor", () => {
    const a = new SimpleData({name: "a"});
    expect(a.address).toBeUndefined();
    const b = a.copy({address: "b"});
    expect(a.address).toBeUndefined();
    expect(b.address).toEqual("b");
  });

});

Disclaimers

• Uses an immutable.js map under the hood; in theory this is good, but I'm not an expert on that vs. just a Object.assign
• I've not done any testing/thinking about inheritance; in case classes this was a bad idea
• The intent is not to model your entire tree of Redux stores, this is "just data classes"

Credits

Inspiration from stimo.