Implement phantom's detecsniff example with puppeteer API.

examples/detectsniff.js

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+/**
+ * Copyright 2017 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+var Browser = require('../lib/Browser');
+
+if (process.argv.length < 3) {
+    console.log('Usage: detectsniff.js <some URL>');
+    return;
+}
+
+var address = process.argv[2];
+console.log('Checking ' + address + '...');
+
+var browser = new Browser();
+browser.newPage().then(async page => {
+    await page.evaluateOnInitialized(function() {
+        (function () {
+            var userAgent = window.navigator.userAgent,
+                platform = window.navigator.platform;
+
+            window.navigator = {
+                appCodeName: 'Mozilla',
+                appName: 'Netscape',
+                cookieEnabled: false,
+                sniffed: false
+            };
+
+            window.navigator.__defineGetter__('userAgent', function () {
+                window.navigator.sniffed = true;
+                return userAgent;
+            });
+
+            window.navigator.__defineGetter__('platform', function () {
+                window.navigator.sniffed = true;
+                return platform;
+            });
+        })();
+    });
+    var success = await page.navigate(address);
+    if (!success) {
+        console.log('FAIL to load the address');
+        browser.close();
+        return;
+    }
+    setTimeout(async function () {
+        var sniffed = await page.evaluate(() => navigator.sniffed);
+        if (sniffed) {
+            console.log('The page tried to sniff the user agent.');
+        } else {
+            console.log('The page did not try to sniff the user agent.');
+        }
+        browser.close();
+    }, 1500);
+});