#define-properties ^{[![Version Badge][npm-version-svg]][package-url]}

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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