| /** |
| * @license |
| * Copyright (C) 2020 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /** |
| * @fileoverview Functions in this file contains some widely used |
| * code patterns. If you noticed a repeated code and none of the existing util |
| * files are appropriate for it - you can wrap the code in a function and put it |
| * here. If you notice that several functions can be group together - create |
| * a separate util file for them. |
| */ |
| |
| /** |
| * Wrapper for the Object.prototype.hasOwnProperty method |
| * |
| * The type guard will also ensure if it returns true, |
| * the obj to check should have the property, see example below: |
| * |
| * @example |
| * |
| * interface A { |
| * a: number; |
| * } |
| * |
| * interface B { |
| * b: number; |
| * } |
| * |
| * function testFn(a: A | B) { |
| * if (hasOwnProperty(a, "a")) { |
| * // with the type guard, typescript now knows that a should be A type |
| * // instead of A | B |
| * a.a = 2; |
| * } |
| * // without the type guard, it will throw error: |
| * // Property 'a' does not exist on type 'A | B'. |
| * } |
| */ |
| export function hasOwnProperty<X extends {}, Y extends PropertyKey>( |
| obj: X, |
| prop: Y |
| ): obj is X & Record<Y, unknown> { |
| return Object.prototype.hasOwnProperty.call(obj, prop); |
| } |
