sinon/lib/sinon/util/core/get-property-descriptor.js

JavaScript test spies, stubs and mocks.

"use strict";

/**
 * @typedef {object} PropertyDescriptor
 * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperty#description
 * @property {boolean} configurable defaults to false
 * @property {boolean} enumerable   defaults to false
 * @property {boolean} writable     defaults to false
 * @property {*} value defaults to undefined
 * @property {Function} get defaults to undefined
 * @property {Function} set defaults to undefined
 */

/*
 * The following type def is strictly speaking illegal in JSDoc, but the expression forms a
 * legal Typescript union type and is understood by Visual Studio and the IntelliJ
 * family of editors. The "TS" flavor of JSDoc is becoming the de-facto standard these
 * days for that reason (and the fact that JSDoc is essentially unmaintained)
 */

/**
 * @typedef {{isOwn: boolean} & PropertyDescriptor} SinonPropertyDescriptor
 * a slightly enriched property descriptor
 * @property {boolean} isOwn true if the descriptor is owned by this object, false if it comes from the prototype
 */

/**
 * Returns a slightly modified property descriptor that one can tell is from the object or the prototype
 *
 * @param {*} object
 * @param {string} property
 * @returns {SinonPropertyDescriptor}
 */
function getPropertyDescriptor(object, property) {
    let proto = object;
    let descriptor;
    const isOwn = Boolean(
        object && Object.getOwnPropertyDescriptor(object, property),
    );

    while (
        proto &&
        !(descriptor = Object.getOwnPropertyDescriptor(proto, property))
    ) {
        proto = Object.getPrototypeOf(proto);
    }

    if (descriptor) {
        descriptor.isOwn = isOwn;
    }

    return descriptor;
}

module.exports = getPropertyDescriptor;