Add evaluate() function

README.md

@@ -386,6 +386,16 @@ Browsershot also can get the body of an html page after JavaScript has been exec
 Browsershot::url('https://example.com')->bodyHtml(); // returns the html of the body
 ```
 
+### Evaluate
+
+Browsershot can get the evaluation of an html page:
+
+```php
+Browsershot::url('https://example.com')
+  ->deviceScaleFactor(2)
+  ->evaluate("window.devicePixelRatio"); // returns 2
+```
+
 ### Misc
 
 #### Setting an arbitrary option

bin/browser.js

@@ -73,10 +73,15 @@ const callChrome = async () => {
             request.options.clip = await element.boundingBox();
         }
 
-        output = await page[request.action](request.options);
+        if(request.action == 'evaluate') {
+            output = await page.evaluate(request.options.pageFunction);
+        } else {
+            output = await page[request.action](request.options);
+            output = output.toString('base64')
+        }
 
         if (!request.options.path) {
-            console.log(output.toString('base64'));
+            console.log(output);
         }
 
         await browser.close();

src/Browsershot.php

@@ -414,6 +414,13 @@ public function savePdf(string $targetPath)
         }
     }
 
+    public function evaluate(string $pageFunction): string
+    {
+        $command = $this->createEvaluateCommand($pageFunction);
+
+        return $this->callBrowser($command);
+    }
+
     public function applyManipulations(string $imagePath)
     {
         Image::load($imagePath)
@@ -471,6 +478,17 @@ public function createPdfCommand($targetPath = null): array
         return $command;
     }
 
+    public function createEvaluateCommand(string $pageFunction): array
+    {
+        $url = $this->html ? $this->createTemporaryHtmlFile() : $this->url;
+
+        $options = [
+            'pageFunction' => $pageFunction,
+        ];
+
+        return $this->createCommand($url, 'evaluate', $options);
+    }
+
     protected function getOptionArgs(): array
     {
         $args = [];
@@ -537,7 +555,7 @@ protected function callBrowser(array $command)
         $process->run();
 
         if ($process->isSuccessful()) {
-            return $process->getOutput();
+            return rtrim($process->getOutput());
         }
 
         if ($process->getExitCode() === 2) {

tests/BrowsershotTest.php

@@ -162,20 +162,6 @@ public function it_can_handle_a_permissions_error()
             ->save($targetPath);
     }
 
-    /** @test */
-    public function it_can_use_the_methods_of_the_image_package()
-    {
-        $targetPath = __DIR__.'/temp/testScreenshot.jpg';
-
-        Browsershot::url('https://example.com')
-            ->format('jpg')
-            ->save($targetPath);
-
-        $this->assertFileExists($targetPath);
-
-        $this->assertMimeType('image/jpeg', $targetPath);
-    }
-
     /** @test */
     public function it_can_create_a_command_to_generate_a_screenshot()
     {
@@ -201,6 +187,7 @@ public function it_can_create_a_command_to_generate_a_screenshot()
                     'height' => 1080,
                 ],
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -228,6 +215,7 @@ public function it_can_create_a_command_to_generate_a_screenshot_and_omit_the_ba
                     'height' => 1080,
                 ],
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -451,6 +439,7 @@ public function it_can_use_given_user_agent()
                 ],
                 'userAgent' => 'my_special_snowflake',
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -473,6 +462,7 @@ public function it_can_set_emulate_media_option()
                 ],
                 'emulateMedia' => 'screen',
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -495,6 +485,7 @@ public function it_can_set_emulate_media_option_to_null()
                 ],
                 'emulateMedia' => null,
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -566,6 +557,7 @@ public function it_can_run_without_sandbox()
                 'args' => [
                     '--no-sandbox',
                 ],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -588,6 +580,7 @@ public function it_can_dismiss_dialogs()
                     'height' => 600,
                 ],
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -610,6 +603,7 @@ public function it_can_ignore_https_errors()
                     'height' => 600,
                 ],
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -631,6 +625,7 @@ public function it_can_use_a_proxy_server()
                     'height' => 600,
                 ],
                 'args' => ['--proxy-server=1.2.3.4:8080'],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -658,6 +653,7 @@ public function it_can_set_arbitrary_options()
                     'baz' => 200,
                 ],
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -735,6 +731,7 @@ public function it_can_wait_until_network_idle()
                     'height' => 600,
                 ],
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
 
@@ -753,6 +750,7 @@ public function it_can_wait_until_network_idle()
                     'height' => 600,
                 ],
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -775,6 +773,7 @@ public function it_can_send_extra_http_headers()
                     'height' => 600,
                 ],
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
@@ -811,7 +810,22 @@ public function it_can_click_on_the_page()
                     'height' => 600,
                 ],
                 'args' => [],
+                'type' => 'png',
             ],
         ], $command);
     }
+
+    /** @test */
+    public function it_can_set_type_of_screenshot()
+    {
+        $targetPath = __DIR__.'/temp/testScreenshot.jpg';
+
+        Browsershot::url('https://example.com')
+            ->setScreenshotType('jpeg')
+            ->save($targetPath);
+
+        $this->assertFileExists($targetPath);
+
+        $this->assertMimeType('image/jpeg', $targetPath);
+    }
 }