Allow WebDriverElement to be used with Browser().execute_script()

docs/javascript.rst

@@ -3,47 +3,106 @@
    license that can be found in the LICENSE file.
 
 .. meta::
-    :description: Executing javascript
+    :description: Execute JavaScript In The Browser
     :keywords: splinter, python, tutorial, javascript
 
 ++++++++++++++++++
 Execute JavaScript
 ++++++++++++++++++
 
-You can easily execute JavaScript, in drivers which support it:
+When using WebDriver-based drivers, you can run JavaScript inside the web
+browser.
+
+Execute
+=======
+
+The `execute_script()` method takes a string containing JavaScript code and
+executes it.
+
+JSON-serializable objects and WebElements can be sent to the browser and used
+by the JavaScript.
+
+Examples
+--------
+
+Change the Background Color of an Element
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. highlight:: python
 
 ::
 
-    browser.execute_script("$('body').empty()")
+    browser = Browser()
+
+    browser.execute_script(
+      "document.querySelector('body').setAttribute('style', 'background-color: red')",
+    )
 
-You can return the result of the script:
+Sending a WebElement to the browser
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 .. highlight:: python
 
 ::
 
-    browser.evaluate_script("4+4") == 8
+    browser = Browser()
+
+    elem = browser.find_by_tag('body').first
+    browser.execute_script(
+      "arguments[0].setAttribute('style', 'background-color: red')",
+      elem,
+    )
+
+
+
+Evaluate
+========
+
+The `evaluate_script()` method takes a string containing a JavaScript
+expression and runs it, then returns the result.
+
+JSON-serializable objects and WebElements can be sent to the browser and used
+by the JavaScript.
+
+Examples
+--------
+
+Get the href from the browser
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. highlight:: python
+
+::
+
+    browser = Browser()
+
+    href = browser.evaluate_script("document.location.href")
+
 
+Cookbook
+========
 
-Example: Manipulate text fields with JavaScript
-+++++++++++++++++++++++++++++++++++++++++++++++++
+Manipulate text fields with JavaScript
+--------------------------------------
 
-Some text input actions cannot be "typed" thru ``browser.fill()``, like new lines and tab characters. Below is en example how to work around this using ``browser.execute_script()``. This is also much faster than ``browser.fill()`` as there is no simulated key typing delay, making it suitable for longer texts.
+Some text input actions cannot be "typed" thru ``browser.fill()``, like new lines and tab characters.
+Below is en example how to work around this using ``browser.execute_script()``.
+This is also much faster than ``browser.fill()`` as there is no simulated key typing delay, making it suitable for longer texts.
 
 ::
 
-   def fast_fill_by_javascript(browser: DriverAPI, elem_id: str, text: str):
+   def fast_fill(browser, query: str, text: str):
        """Fill text field with copy-paste, not by typing key by key.
 
        Otherwise you cannot type enter or tab.
 
-       :param id: CSS id of the textarea element to fill
+       Arguments:
+          query: CSS id of the textarea element to fill
        """
        text = text.replace("\t", "\\t")
        text = text.replace("\n", "\\n")
 
-       # Construct a JavaScript snippet that is executed on the browser sdie
-       snippet = f"""document.querySelector("#{elem_id}").value = "{text}";"""
-       browser.execute_script(snippet)
+       elem = browser.find_by_css(query).first
+       # Construct a JavaScript snippet that is executed on the browser side
+       script = f"arguments[0].value = "{text}";"
+       browser.execute_script(script, elem)

splinter/driver/__init__.py

@@ -107,35 +107,47 @@ def get_iframe(self, name: Any) -> Any:
         """
         raise NotImplementedError("%s doesn't support frames." % self.driver_name)
 
-    def execute_script(self, script: str, *args: str) -> Any:
-        """Execute a piece of JavaScript in the browser.
+    def execute_script(self, script: str, *args: Any) -> Any:
+        """Execute JavaScript in the current browser window.
+
+        The code is assumed to be synchronous.
 
         Arguments:
-            script (str): The piece of JavaScript to execute.
+            script (str): The JavaScript code to execute.
+            args: Any of:
+                - JSON-serializable objects.
+                - WebElement.
+                These will be available to the JavaScript as the `arguments` object.
 
         Example:
 
-            >>> browser.execute_script('document.getElementById("body").innerHTML = "<p>Hello world!</p>"')
+            >>> Browser().execute_script('document.querySelector("body").innerHTML = "<p>Hello world!</p>"')
         """
         raise NotImplementedError(
-            "%s doesn't support execution of arbitrary JavaScript." % self.driver_name,
+            f"{self.driver_name} doesn't support execution of arbitrary JavaScript.",
         )
 
-    def evaluate_script(self, script: str, *args: str) -> Any:
-        """
-        Similar to :meth:`execute_script <DriverAPI.execute_script>` method.
+    def evaluate_script(self, script: str, *args: Any) -> Any:
+        """Evaluate JavaScript in the current browser window and return the completion value.
 
-        Execute javascript in the browser and return the value of the expression.
+        The code is assumed to be synchronous.
 
         Arguments:
-            script (str): The piece of JavaScript to execute.
+            script (str): The JavaScript code to execute.
+            args: Any of:
+                - JSON-serializable objects.
+                - WebElement.
+                These will be available to the JavaScript as the `arguments` object.
+
+        Returns:
+            The result of the code's execution.
 
         Example:
 
-            >>> assert 4 == browser.evaluate_script('2 + 2')
+            >>> assert 4 == Browser().evaluate_script('2 + 2')
         """
         raise NotImplementedError(
-            "%s doesn't support evaluation of arbitrary JavaScript." % self.driver_name,
+            f"{self.driver_name} doesn't support evaluation of arbitrary JavaScript.",
         )
 
     def find_by_css(self, css_selector: str) -> ElementList:

splinter/driver/webdriver/__init__.py

@@ -7,7 +7,7 @@
 import time
 import warnings
 from contextlib import contextmanager
-from typing import Optional
+from typing import Dict, Optional
 
 from selenium.common.exceptions import ElementClickInterceptedException
 from selenium.common.exceptions import MoveTargetOutOfBoundsException
@@ -316,11 +316,29 @@ def forward(self):
     def reload(self):
         self.driver.refresh()
 
+    def _script_prepare_args(self, args) -> list:
+        """Modify user arguments sent to execute_script() and evaluate_script().
+
+        If a WebDriverElement or ShadowRootElement is given,
+        replace it with their Element ID.
+        """
+        result = []
+
+        for item in args:
+            if isinstance(item, (WebDriverElement, ShadowRootElement)):
+                result.append(item._as_id_dict())
+            else:
+                result.append(item)
+
+        return result
+
     def execute_script(self, script, *args):
-        return self.driver.execute_script(script, *args)
+        converted_args = self._script_prepare_args(args)
+        return self.driver.execute_script(script, *converted_args)
 
     def evaluate_script(self, script, *args):
-        return self.driver.execute_script("return %s" % script, *args)
+        converted_args = self._script_prepare_args(args)
+        return self.driver.execute_script(f"return {script}", *converted_args)
 
     def is_element_present(self, finder, selector, wait_time=None):
         wait_time = wait_time or self.wait_time
@@ -694,6 +712,15 @@ def __init__(self, element, parent):
         self.wait_time = self.parent.wait_time
         self.element_class = self.parent.element_class
 
+    def _as_id_dict(self) -> Dict[str, str]:
+        """Get the canonical object to identify an element by it's ID.
+
+        When sent to the browser, it will be used to build an Element object.
+
+        Not to be confused with the 'id' tag on an element.
+        """
+        return {"shadow-6066-11e4-a52e-4f735466cecf": self._element._id}
+
     def _find(self, by: By, selector, wait_time=None):
         return self.find_by(
             self._element.find_elements,
@@ -743,6 +770,15 @@ def _set_value(self, value):
     def __getitem__(self, attr):
         return self._element.get_attribute(attr)
 
+    def _as_id_dict(self) -> Dict[str, str]:
+        """Get the canonical object to identify an element by it's ID.
+
+        When sent to the browser, it will be used to build an Element object.
+
+        Not to be confused with the 'id' tag on an element.
+        """
+        return {"element-6066-11e4-a52e-4f735466cecf": self._element._id}
+
     @property
     def text(self):
         return self._element.text

tests/tests_webdriver/test_javascript/test_evaluate_script.py

@@ -0,0 +1,76 @@
+import pytest
+
+from selenium.common.exceptions import JavascriptException
+
+
+def test_evaluate_script_valid(browser, app_url):
+    """Scenario: Evaluating JavaScript Returns The Code's Result
+
+    When I evaluate JavaScript code
+    Then the result of the evaluation is returned
+    """
+    browser.visit(app_url)
+
+    document_href = browser.evaluate_script("document.location.href")
+    assert app_url == document_href
+
+
+def test_evaluate_script_valid_args(browser, app_url):
+    """Scenario: Execute Valid JavaScript With Arguments
+
+    When I execute valid JavaScript code which modifies the DOM
+    And I send arguments to the web browser
+    Then the arguments are available for use
+    """
+    browser.visit(app_url)
+
+    browser.evaluate_script(
+        "document.querySelector('body').innerHTML = arguments[0] + arguments[1]",
+        "A String And ",
+        "Another String",
+    )
+
+    elem = browser.find_by_tag("body").first
+    assert elem.value == "A String And Another String"
+
+
+def test_evaluate_script_valid_args_element(browser, app_url):
+    """Scenario: Execute Valid JavaScript
+
+    When I execute valid JavaScript code
+    And I send an Element to the browser as an argument
+    Then the modifications are seen in the document
+    """
+    browser.visit(app_url)
+
+    elem = browser.find_by_id("firstheader").first
+    elem_text = browser.evaluate_script("arguments[0].innerHTML", elem)
+    assert elem_text == "Example Header"
+
+
+def test_evaluate_script_invalid(browser, app_url):
+    """Scenario: Evaluate Invalid JavaScript.
+
+    When I evaluate invalid JavaScript code
+    Then an error is raised
+    """
+    browser.visit(app_url)
+
+    with pytest.raises(JavascriptException):
+        browser.evaluate_script("invalid.thisIsNotGood()")
+
+
+def test_evaluate_script_invalid_args(browser, app_url):
+    """Scenario: Execute Valid JavaScript
+
+    When I execute valid JavaScript code which modifies the DOM
+    And I send an object to the browser which is not JSON serializable
+    Then an error is raised
+    """
+    browser.visit(app_url)
+
+    def unserializable():
+        "You can't JSON serialize a function."
+
+    with pytest.raises(TypeError):
+        browser.evaluate_script("arguments[0]", unserializable)