ObjectExtensions.ensure

Simple JavaScript object type checker.

API

declare module ObjectExtensions {
    function ensure(object: any, type: any): boolean;
}

Example

// Primitive-typed objects
ObjectExtensions.ensure("abc", "string"); // true
ObjectExtensions.ensure(true, "boolean"); // true

// Primitive-typed properties
ObjectExtensions.ensure({ str: "abc" }, { str: "string"}); // true
ObjectExtensions.ensure({ str: 3 }, { str: "string"}); // false

// Non-primitive-typed properties
ObjectExtensions.ensure({ str: new String("abc") }, { str: String }); // true
ObjectExtensions.ensure({ body: document.body }, { body: HTMLBodyElement }); // true
ObjectExtensions.ensure({ body: document.body }, { body: HTMLElement }); // true
ObjectExtensions.ensure({ body: document.body }, { body: HTMLSpanElement }); // false

// Type unions
ObjectExtensions.ensure("abc", ["string", "boolean"]); // true
ObjectExtensions.ensure(true, ["string", "boolean"]); // true
ObjectExtensions.ensure(0, ["string", "boolean"]); // false
ObjectExtensions.ensure(
  {
    mado: "homu",
    kudasai: true
  },
  {
    mado: ["string", "function"],
    kudasai: "boolean"
  }); // true

// Tuples
ObjectExtensions.ensure(["quintet", 5], { 0: "string", 1: "number" }); // true

// Nested type checking, or "structure checking"
ObjectExtensions.ensure({ obj: { prop: 3 } }, { obj: { prop: "number" } }); // true
ObjectExtensions.ensure(
  {
    obj: {
      prop: document,
      other: true
    },
    homu: {
      kawaii: 4,
      utsukushii: true
    }
  },
  {
    obj: {
      prop: Document,
      other: "boolean"
    },
    homu: {
      kawaii: "number",
      utsukushii: "boolean"
    }
  }); // true

// Checking mere existence
ObjectExtensions.ensure({ prop: true }, { prop: null }); // true
ObjectExtensions.ensure({ prop: true }, { src: null }); // false

// Checking nonexistence
ObjectExtensions.ensure({ prop: true }, { prop: undefined }); // false
ObjectExtensions.ensure({ prop: true }, { src: undefined }); // true