Add is.domElement() (#11)

index.js

@@ -161,6 +161,18 @@ is.inRange = (x, range) => {
 	throw new TypeError(`Invalid range: ${util.inspect(range)}`);
 };
 
+const NODE_TYPE_ELEMENT = 1;
+const DOM_PROPERTIES_TO_CHECK = [
+	'innerHTML',
+	'ownerDocument',
+	'style',
+	'attributes',
+	'nodeValue'
+];
+
+is.domElement = x => is.object(x) && x.nodeType === NODE_TYPE_ELEMENT && is.string(x.nodeName) &&
+	!is.plainObject(x) && DOM_PROPERTIES_TO_CHECK.every(property => property in x);
+
 is.infinite = x => x === Infinity || x === -Infinity;
 
 const isEmptyStringOrArray = x => (is.string(x) || is.array(x)) && x.length === 0;

package.json

@@ -44,6 +44,7 @@
   ],
   "devDependencies": {
     "ava": "*",
+    "jsdom": "^9.12.0",
     "xo": "*"
   }
 }

readme.md

@@ -145,11 +145,14 @@ Check if `value` (number) is in the range of `0` to `upperBound`.
 is.inRange(3, 10);
 ```
 
+##### .domElement(value)
+
+Returns `true` if `value` is a DOM Element.
+
 ##### .infinite(value)
 
 Check if `value` is `Infinity` or `-Infinity`.
 
-
 ##### .empty(value)
 
 Returns `true` if `value` is falsy or an empty string, array, object, map, or set.

test.js

@@ -1,5 +1,6 @@
 import util from 'util';
 import test from 'ava';
+import {jsdom} from 'jsdom';
 import m from '.';
 
 const isNode8orHigher = Number(process.versions.node.split('.')[0]) >= 8;
@@ -7,6 +8,9 @@ const isNode8orHigher = Number(process.versions.node.split('.')[0]) >= 8;
 const PromiseSubclassFixture = class extends Promise {};
 const ErrorSubclassFixture = class extends Error {};
 
+const document = jsdom();
+const createDomElement = el => document.createElement(el);
+
 const types = new Map([
 	['undefined', undefined],
 	['null', null],
@@ -90,6 +94,22 @@ const types = new Map([
 		new Object() // eslint-disable-line no-new-object
 	]],
 	['integer', 6],
+	['domElement', [
+		'div',
+		'input',
+		'span',
+		'img',
+		'canvas',
+		'script'
+	].map(createDomElement)],
+	['non-domElements', [
+		document.createTextNode('data'),
+		document.createProcessingInstruction('xml-stylesheet', 'href="mycss.css" type="text/css"'),
+		document.createComment('This is a comment'),
+		document,
+		document.implementation.createDocumentType('svg:svg', '-//W3C//DTD SVG 1.1//EN', 'http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd'),
+		document.createDocumentFragment()
+	]],
 	['infinite', [
 		Infinity,
 		-Infinity
@@ -370,6 +390,11 @@ test('is.inRange', t => {
 	});
 });
 
+test('is.domElement', t => {
+	testType(t, 'domElement');
+	t.false(m.domElement({nodeType: 1, nodeName: 'div'}));
+});
+
 test('is.infinite', t => {
 	testType(t, 'infinite', ['number']);
 });