#define-properties ^{[![Version Badge][npm-version-svg]][package-url]} [![Build Status][travis-svg]][travis-url] [![dependency status][deps-svg]][deps-url] [![dev dependency status][dev-deps-svg]][dev-deps-url] [![License][license-image]][license-url] [![Downloads][downloads-image]][downloads-url] [![npm badge][npm-badge-png]][package-url] [![browser support][testling-svg]][testling-url] Define multiple non-enumerable properties at once. Uses `Object.defineProperty` when available; falls back to standard assignment in older engines. Existing properties are not overridden. Accepts a map of property names to a predicate that, when true, force-overrides. ## Example ```js var define = require('define-properties'); var assert = require('assert'); var obj = define({ a: 1, b: 2 }, { a: 10, b: 20, c: 30 }); assert(obj.a === 1); assert(obj.b === 2); assert(obj.c === 30); if (define.supportsDescriptors) { assert.deepEqual(Object.keys(obj), ['a', 'b']); assert.deepEqual(Object.getOwnPropertyDescriptor(obj, 'c'), { configurable: true, enumerable: false, value: 30, writable: false }); } ``` Then, with predicates: ```js var define = require('define-properties'); var assert = require('assert'); var obj = define({ a: 1, b: 2, c: 3 }, { a: 10, b: 20, c: 30 }, { a: function () { return false; }, b: function () { return true; } }); assert(obj.a === 1); assert(obj.b === 20); assert(obj.c === 3); if (define.supportsDescriptors) { assert.deepEqual(Object.keys(obj), ['a', 'c']); assert.deepEqual(Object.getOwnPropertyDescriptor(obj, 'b'), { configurable: true, enumerable: false, value: 20, writable: false }); } ``` ## Tests Simply clone the repo, `npm install`, and run `npm test` [package-url]: https://npmjs.org/package/define-properties [npm-version-svg]: http://versionbadg.es/ljharb/define-properties.svg [travis-svg]: https://travis-ci.org/ljharb/define-properties.svg [travis-url]: https://travis-ci.org/ljharb/define-properties [deps-svg]: https://david-dm.org/ljharb/define-properties.svg [deps-url]: https://david-dm.org/ljharb/define-properties [dev-deps-svg]: https://david-dm.org/ljharb/define-properties/dev-status.svg [dev-deps-url]: https://david-dm.org/ljharb/define-properties#info=devDependencies [testling-svg]: https://ci.testling.com/ljharb/define-properties.png [testling-url]: https://ci.testling.com/ljharb/define-properties [npm-badge-png]: https://nodei.co/npm/define-properties.png?downloads=true&stars=true [license-image]: http://img.shields.io/npm/l/define-properties.svg [license-url]: LICENSE [downloads-image]: http://img.shields.io/npm/dm/define-properties.svg [downloads-url]: http://npm-stat.com/charts.html?package=define-properties