code: // Licensed to the Software Freedom Conservancy (SFC) under one
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  // to you 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
  //
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  // software distributed under the License is distributed on an
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  // KIND, either express or implied.  See the License for the
  // specific language governing permissions and limitations
  // under the License.
  
  package org.openqa.selenium;
  
  import java.util.Collections;
  import java.util.Set;
  import java.util.stream.Collectors;
  import org.openqa.selenium.internal.Require;
  
  /**
   * Indicates that a driver can execute JavaScript, providing access to the mechanism to do so.
   *
   * <p>Because of cross domain policies browsers enforce your script execution may fail unexpectedly
   * and without adequate error messaging. This is particularly pertinent when creating your own XHR
   * request or when trying to access another frame. Most times when troubleshooting failure it's best
   * to view the browser's console after executing the WebDriver request.
   */
  public interface JavascriptExecutor {
    /**
     * Executes JavaScript in the context of the currently selected frame or window. The script
     * fragment provided will be executed as the body of an anonymous function.
     *
     * <p>Within the script, use <code>document</code> to refer to the current document. Note that
     * local variables will not be available once the script has finished executing, though global
     * variables will persist.
     *
     * <p>If the script has a return value (i.e. if the script contains a <code>return</code>
     * statement), then the following steps will be taken:
     *
     * <ul>
     *   <li>For an HTML element, this method returns a WebElement
     *   <li>For a decimal, a Double is returned
     *   <li>For a non-decimal number, a Long is returned
     *   <li>For a boolean, a Boolean is returned
     *   <li>For all other cases, a String is returned.
     *   <li>For an array, return a List&lt;Object&gt; with each object following the rules above. We
     *       support nested lists.
     *   <li>For a map, return a Map&lt;String, Object&gt; with values following the rules above.
     *   <li>Unless the value is null or there is no return value, in which null is returned
     * </ul>
     *
     * <p>Arguments must be a number, a boolean, a String, WebElement, or a List of any combination of
     * the above. An exception will be thrown if the arguments do not meet these criteria. The
     * arguments will be made available to the JavaScript via the "arguments" magic variable, as if
     * the function were called via "Function.apply"
     *
     * @param script The JavaScript to execute
     * @param args The arguments to the script. May be empty
     * @return One of Boolean, Long, Double, String, List, Map or WebElement. Or null.
     */
    Object executeScript(String script, Object... args);
  
    /**
     * Execute an asynchronous piece of JavaScript in the context of the currently selected frame or
     * window. Unlike executing {@link #executeScript(String, Object...) synchronous JavaScript},
     * scripts executed with this method must explicitly signal they are finished by invoking the
     * provided callback. This callback is always injected into the executed function as the last
     * argument.
     *
     * <p>The first argument passed to the callback function will be used as the script's result. This
     * value will be handled as follows:
     *
     * <ul>
     *   <li>For an HTML element, this method returns a WebElement
     *   <li>For a number, a Long is returned
     *   <li>For a boolean, a Boolean is returned
     *   <li>For all other cases, a String is returned.
     *   <li>For an array, return a List&lt;Object&gt; with each object following the rules above. We
     *       support nested lists.
     *   <li>For a map, return a Map&lt;String, Object&gt; with values following the rules above.
     *   <li>Unless the value is null or there is no return value, in which null is returned
     * </ul>
     *
     * <p>The default timeout for a script to be executed is 0ms. In most cases, including the
     * examples below, one must set the script timeout {@link
     * WebDriver.Timeouts#scriptTimeout(java.time.Duration)} beforehand to a value sufficiently large
     * enough.
     *
     * <p>Example #1: Performing a sleep in the browser under test.
     *
     * <pre>{@code
     * long start = System.currentTimeMillis();
     * ((JavascriptExecutor) driver).executeAsyncScript(
     *     "window.setTimeout(arguments[arguments.length - 1], 500);");
     * System.out.println(
     *     "Elapsed time: " + (System.currentTimeMillis() - start));
     * }</pre>
     *
     * <p>Example #2: Synchronizing a test with an AJAX application:
     *
     * <pre>{@code
     * WebElement composeButton = driver.findElement(By.id("compose-button"));
     * composeButton.click();
     * ((JavascriptExecutor) driver).executeAsyncScript(
     *     "var callback = arguments[arguments.length - 1];" +
     *     "mailClient.getComposeWindowWidget().onload(callback);");
     * driver.switchTo().frame("composeWidget");
     * driver.findElement(By.id("to")).sendKeys("bog@example.com");
     * }</pre>
     *
     * <p>Example #3: Injecting a XMLHttpRequest and waiting for the result:
     *
     * <pre>{@code
     * Object response = ((JavascriptExecutor) driver).executeAsyncScript(
     *     "var callback = arguments[arguments.length - 1];" +
     *     "var xhr = new XMLHttpRequest();" +
     *     "xhr.open('GET', '/resource/data.json', true);" +
     *     "xhr.onreadystatechange = function() {" +
     *     "  if (xhr.readyState == 4) {" +
     *     "    callback(xhr.responseText);" +
     *     "  }" +
     *     "};" +
     *     "xhr.send();");
     * JsonObject json = new JsonParser().parse((String) response);
     * assertEquals("cheese", json.get("food").getAsString());
     * }</pre>
     *
     * <p>Script arguments must be a number, a boolean, a String, WebElement, or a List of any
     * combination of the above. An exception will be thrown if the arguments do not meet these
     * criteria. The arguments will be made available to the JavaScript via the "arguments" variable.
     *
     * @param script The JavaScript to execute.
     * @param args The arguments to the script. May be empty.
     * @return One of Boolean, Long, String, List, Map, WebElement, or null.
     * @see WebDriver.Timeouts#scriptTimeout(java.time.Duration)
     */
    Object executeAsyncScript(String script, Object... args);
  
    /**
     * Commonly used scripts may be "pinned" to the WebDriver session, allowing them to be called
     * efficiently by their handle rather than sending the entire script across the wire for every
     * call.
     *
     * <p>The default implementation of this adheres to the API's expectations but is inefficient.
     *
     * @see #executeScript(ScriptKey, Object...)
     * @param script The Javascript to execute.
     * @return A handle which may later be used in {@link #executeScript(ScriptKey, Object...)}
     * @throws JavascriptException If the script cannot be pinned for some reason.
     */
    default ScriptKey pin(String script) {
      Require.nonNull("Script to pin", script);
      return UnpinnedScriptKey.pin(this, script);
    }
  
    /**
     * Deletes the reference to a script that has previously been pinned. Subsequent calls to {@link
     * #executeScript(ScriptKey, Object...)} will fail for the given {@code key}.
     */
    default void unpin(ScriptKey key) {
      Require.nonNull("Key to unpin", key);
      Require.stateCondition(
          key instanceof UnpinnedScriptKey, "Script key should have been generated by this driver");
  
      UnpinnedScriptKey.unpin(this, (UnpinnedScriptKey) key);
    }
  
    /**
     * @return The {@link ScriptKey}s of all currently pinned scripts.
     */
    default Set<ScriptKey> getPinnedScripts() {
      return Collections.unmodifiableSet(
          UnpinnedScriptKey.getPinnedScripts(this).stream()
              .map(key -> (ScriptKey) key)
              .collect(Collectors.toSet()));
    }
  
    /**
     * Calls a script by the {@link ScriptKey} returned by {@link #pin(String)}. This can be thought
     * of as inlining the pinned script and simply calling {@link #executeScript(String, Object...)}.
     *
     * @see #executeScript(String, Object...)
     */
    default Object executeScript(ScriptKey key, Object... args) {
      Require.stateCondition(
          key instanceof UnpinnedScriptKey, "Script key should have been generated by this driver");
  
      if (!getPinnedScripts().contains(key)) {
        throw new JavascriptException("Script is unpinned");
      }
  
      return executeScript(((UnpinnedScriptKey) key).getScript(), args);
    }
  }
  