@barchart/common-js/specifications/Exists.js

Library of common JavaScript utilities

const Specification = require('./Specification');

const Null = require('./Null'),
	Undefined = require('./Undefined');

module.exports = (() => {
	'use strict';

	/**
	 * A {@link Specification} that passes when the value of the item passed to
	 * the constructor is neither null or undefined.
	 *
	 * @public
	 * @extends {Specification}
	 */
	class Exists extends Specification {
		constructor() {
			super();

			const n = new Null();
			const u = new Undefined();

			this._wrapped = n.or(u).not();
		}

		_evaluate(data) {
			return this._wrapped.evaluate(data);
		}

		toString() {
			return '[Exists]';
		}
	}

	return Exists;
})();