Use optional npm dependencies to shim DOMParser and WebSocket in node

Author: LeartS

package-lock.json

@@ -73,5 +73,9 @@
     "sinon-qunit": "~2.0.0",
     "yarpm": "^0.2.1"
   },
-  "dependencies": {}
+  "dependencies": {},
+  "optionalDependencies": {
+    "ws": "^7.0.0",
+    "xmldom": "^0.1.27"
+  }
 }

package.json

@@ -8,6 +8,7 @@
 /* global window, setTimeout, clearTimeout, XMLHttpRequest, ActiveXObject */
 
 import core from './core';
+import { DOMParser } from './shims'
 
 const Strophe = core.Strophe;
 const $build = core.$build;

src/bosh.js

@@ -9,6 +9,7 @@
 import MD5 from './md5';
 import SHA1 from './sha1';
 import utils from './utils';
+import * as shims from './shims';
 
 /** Function: $build
  *  Create a Strophe.Builder.
@@ -330,26 +331,6 @@ const Strophe = {
      */
     _xmlGenerator: null,
 
-    /** PrivateFunction: _makeGenerator
-     *  _Private_ function that creates a dummy XML DOM document to serve as
-     *  an element and text node generator.
-     */
-    _makeGenerator: function () {
-        let doc;
-        // IE9 does implement createDocument(); however, using it will cause the browser to leak memory on page unload.
-        // Here, we test for presence of createDocument() plus IE's proprietary documentMode attribute, which would be
-        // less than 10 in the case of IE9 and below.
-        if (document.implementation.createDocument === undefined ||
-                    document.implementation.createDocument && document.documentMode && document.documentMode < 10) {
-            doc = this._getIEXmlDom();
-            doc.appendChild(doc.createElement('strophe'));
-        } else {
-            doc = document.implementation
-                .createDocument('jabber:client', 'strophe', null);
-        }
-        return doc;
-    },
-
     /** Function: xmlGenerator
      *  Get the DOM document to generate elements.
      *
@@ -358,45 +339,11 @@ const Strophe = {
      */
     xmlGenerator: function () {
         if (!Strophe._xmlGenerator) {
-            Strophe._xmlGenerator = Strophe._makeGenerator();
+            Strophe._xmlGenerator = shims.getDummyXMLDOMDocument()
         }
         return Strophe._xmlGenerator;
     },
 
-    /** PrivateFunction: _getIEXmlDom
-     *  Gets IE xml doc object
-     *
-     *  Returns:
-     *    A Microsoft XML DOM Object
-     *  See Also:
-     *    http://msdn.microsoft.com/en-us/library/ms757837%28VS.85%29.aspx
-     */
-    _getIEXmlDom : function() {
-        let doc = null;
-        const docStrings = [
-            "Msxml2.DOMDocument.6.0",
-            "Msxml2.DOMDocument.5.0",
-            "Msxml2.DOMDocument.4.0",
-            "MSXML2.DOMDocument.3.0",
-            "MSXML2.DOMDocument",
-            "MSXML.DOMDocument",
-            "Microsoft.XMLDOM"
-        ];
-
-        for (let d=0; d<docStrings.length; d++) {
-            if (doc === null) {
-                try {
-                    doc = new ActiveXObject(docStrings[d]);
-                } catch (e) {
-                    doc = null;
-                }
-            } else {
-                break;
-            }
-        }
-        return doc;
-    },
-
     /** Function: xmlElement
      *  Create an XML DOM element.
      *
@@ -512,8 +459,8 @@ const Strophe = {
     xmlHtmlNode: function (html) {
         let node;
         //ensure text is escaped
-        if (DOMParser) {
-            const parser = new DOMParser();
+        if (shims.DOMParser) {
+            const parser = new shims.DOMParser();
             node = parser.parseFromString(html, "text/xml");
         } else {
             node = new ActiveXObject("Microsoft.XMLDOM");
@@ -1160,7 +1107,7 @@ Strophe.Builder.prototype = {
      *    The Strophe.Builder object.
      */
     h: function (html) {
-        const fragment = document.createElement('body');
+        const fragment = Strophe.xmlGenerator().createElement('body');
         // force the browser to try and fix any invalid HTML tags
         fragment.innerHTML = html;
         // copy cleaned html into an xml dom
@@ -3505,7 +3452,6 @@ Strophe.SASLOAuthBearer.prototype = new Strophe.SASLMechanism("OAUTHBEARER", tru
 Strophe.SASLOAuthBearer.prototype.test = function(connection) {
     return connection.pass !== null;
 };
-
 Strophe.SASLOAuthBearer.prototype.onChallenge = function(connection) {
     let auth_str = 'n,';
     if (connection.authcid !== null) {

src/core.js

@@ -0,0 +1,120 @@
+/*
+ * This module provides uniform
+ * Shims APIs and globals that are not present in all JS environments,
+ * the most common example for Strophe being browser APIs like WebSocket
+ * and DOM that don't exist under nodejs.
+ *
+ * Usually these will be supplied in nodejs by conditionally requiring a
+ * NPM module that provides a compatible implementation.
+ */
+
+/**
+ * WHATWG WebSockets API
+ * https://www.w3.org/TR/websockets/
+ *
+ * Interface to use the web socket protocol
+ *
+ * Used implementations:
+ * - supported browsers: built-in in WebSocket global
+ *   https://developer.mozilla.org/en-US/docs/Web/API/WebSocket#Browser_compatibility
+ * - nodejs: use standard-compliant 'ws' module
+ *   https://www.npmjs.com/package/ws
+ */
+function getWebSocketImplementation () {
+    let WebSocketImplementation = WebSocket
+    if (typeof WebSocketImplementation === 'undefined') {
+        try {
+            WebSocketImplementation = require('ws');
+        } catch (err) {
+            throw new Error('You must install the "ws" package to use Strophe in nodejs.');
+        }
+    }
+    return WebSocketImplementation
+}
+export const WebSocket = getWebSocketImplementation()
+
+/**
+ * DOMParser
+ * https://w3c.github.io/DOM-Parsing/#the-domparser-interface
+ *
+ * Interface to parse XML strings into Document objects
+ *
+ * Used implementations:
+ * - supported browsers: built-in in DOMParser global
+ *   https://developer.mozilla.org/en-US/docs/Web/API/DOMParser#Browser_compatibility
+ * - nodejs: use 'xmldom' module
+ *   https://www.npmjs.com/package/xmldom
+ */
+function getDOMParserImplementation () {
+    let DOMParserImplementation = DOMParser
+    if (typeof DOMParserImplementation === 'undefined') {
+        try {
+            DOMParserImplementation = require('xmldom').DOMParser;
+        } catch (err) {
+            throw new Error('You must install the "xmldom" package to use Strophe in nodejs.');
+        }
+    }
+    return DOMParserImplementation
+}
+export const DOMParser = getDOMParserImplementation()
+
+/**
+ *  Gets IE xml doc object. Used by getDummyXMLDocument shim.
+ *
+ *  Returns:
+ *    A Microsoft XML DOM Object
+ *  See Also:
+ *    http://msdn.microsoft.com/en-us/library/ms757837%28VS.85%29.aspx
+ */
+function _getIEXmlDom () {
+    const docStrings = [
+        "Msxml2.DOMDocument.6.0",
+        "Msxml2.DOMDocument.5.0",
+        "Msxml2.DOMDocument.4.0",
+        "MSXML2.DOMDocument.3.0",
+        "MSXML2.DOMDocument",
+        "MSXML.DOMDocument",
+        "Microsoft.XMLDOM"
+    ];
+    for (let d = 0; d < docStrings.length; d++) {
+        try {
+            const doc = new ActiveXObject(docStrings[d]);
+            return doc
+        } catch (e) {
+            // Try next one
+        }
+    }
+}
+
+/**
+ * Creates a dummy XML DOM document to serve as an element and text node generator.
+ *
+ * Used implementations:
+ *  - IE < 10: avoid using createDocument() due to a memory leak, use ie-specific
+ *    workaround
+ *  - other supported browsers: use document's createDocument
+ *  - nodejs: use 'xmldom'
+ */
+export function getDummyXMLDOMDocument () {
+    // nodejs
+    if (typeof document === 'undefined') {
+        try {
+            const DOMImplementation = require('xmldom').DOMImplementation;
+            return new DOMImplementation().createDocument('jabber:client', 'strophe', null);
+        } catch (err) {
+            throw new Error('You must install the "xmldom" package to use Strophe in nodejs.');
+        }
+    }
+    // IE < 10
+    if (
+        document.implementation.createDocument === undefined ||
+        document.implementation.createDocument && document.documentMode && document.documentMode < 10
+    ) {
+        const doc = _getIEXmlDom();
+        doc.appendChild(doc.createElement('strophe'));
+        return doc
+    }
+    // All other supported browsers
+    return document.implementation.createDocument('jabber:client', 'strophe', null)
+}
+

src/shims.js

@@ -8,6 +8,7 @@
 /* global window, clearTimeout, WebSocket, DOMParser */
 
 import core from './core';
+import { WebSocket, DOMParser } from './shims';
 
 const Strophe = core.Strophe;
 const $build = core.$build;