feat(ui): Add TS definitions for "is" utils (#14456)

ui/types/utils.d.ts

@@ -19,6 +19,7 @@ export * from './utils/dom';
 export * from './utils/event';
 export * from './utils/format';
 export * from './utils/scroll';
+export * from './utils/is';
 export * from './utils/run-sequential-promises';
 
 import { VueStyleObjectProp } from "./api/vue-prop-types";

ui/types/utils/is.d.ts

@@ -0,0 +1,67 @@
+interface is {
+  /**
+   * Recursively checks if one Object is equal to another.
+   * Also supports Map, Set, ArrayBuffer, Regexp, Date, and many more.
+   *
+   * @example
+   * const objA = { foo: 1, bar: { baz: 2 } }
+   * const objB = { foo: 1, bar: { baz: 2 } }
+   * objA === objB // false
+   * is.deepEqual(objA, objB) // true
+   */
+  // Can't do it both ways, see: https://github.com/microsoft/TypeScript/issues/26916#issuecomment-555691585
+  deepEqual<T>(obj1: T, obj2: unknown): obj2 is T;
+
+  /**
+   * Checks if a value is an object.
+   * Note: Map, Set, ArrayBuffer, Regexp, Date, etc. are also objects,
+   * but null and Arrays are not.
+   *
+   * @example
+   * is.object({}) // true
+   * is.object([]) // false
+   * is.object(null) // false
+   * is.object(1) // false
+   * is.object(new Map()) // true
+   * is.object(new Set()) // true
+   */
+  object<T>(val: T): val is Record<any, any>;
+
+  /**
+   * Checks if a value is a Date object.
+   *
+   * @see `date.isValid()` If you want to check if a value is a valid date string or number
+   *
+   * @example
+   * is.date(new Date()) // true
+   * is.date(Date.now()) // false
+   * is.date(new Date('2022-09-24T11:00:00.000Z')) // true
+   * is.date('2022-09-24') // false
+   */
+  date(val: unknown): val is Date;
+
+  /**
+   * Checks if a value is a RegExp.
+   *
+   * @example <caption>Literal notation</caption>
+   * is.regexp(/foo/); // true
+   * @example <caption>Constructor</caption>
+   * is.regexp(new RegExp('bar', 'g')); // true
+   */
+  regexp(val: unknown): val is RegExp;
+
+  /**
+   * Checks if a value is a finite number.
+   * Note: BigInts, NaN, and Infinity values are not considered as numbers.
+   *
+   * @example
+   * is.number(1); // true
+   * is.number('1'); // false
+   * is.number(1n); // false
+   * is.number(NaN); // false
+   * is.number(Infinity); // false
+   */
+  number(val: unknown): val is number;
+}
+
+export declare const is: is;