Using WebDriver JS Executor to execute a .js file --> Null Pointer Exception

Question

I am trying to implement a script I found online that automatically loads jQuery into sites that don't currently have them. I am using Selenium Webdriver's JS Executor function; however, it keeps returning a Null Pointer Exception. I tried to look everywhere for an answer, but can't seem to understand what's going on. What gives?

/** Browser automation driver for this test instance. */
private WebDriver driver;

/** JavaScript Executor for this test instance. */
private JavascriptExecutor js = (JavascriptExecutor) driver;

//...Firefox browser initialized here

 public void JQuerify(final String Url){
    ReporterNG.log("Opening a webpage at: " + Url);
    driver.get(Url);

    ReporterNG.log("Converting JS file to a String");

        String jQueryLoader = getLoadJQuery();

        // give jQuery time to load asynchronously
        driver.manage().timeouts().setScriptTimeout(10, TimeUnit.SECONDS);

        js.executeAsyncScript(jQueryLoader);
        //THE PROBLEM ALWAYS OCCURS WITH THIS ^^^^^

        ReporterNG.log("jQuery loaded!");
        //THIS NEVER PRINTS OUT DUE TO THE ERROR ^^^^
}

 /** dynamically load jQuery */
public static String getLoadJQuery(){
    String LoadJQuery = "(function(jqueryUrl, callback) {\n" +
            "if (typeof jqueryUrl != 'string') {" +
            "jqueryUrl = 'https://ajax.googleapis.com/ajax/libs/jquery/1.10.1/jquery.min.js';\n" +
            "}\n" +
            "if (typeof jQuery == 'undefined') {\n" +
            "var script = document.createElement('script');\n" +
            "var head = document.getElementsByTagName('head')[0];\n" +
            "var done = false;\n" +
            "script.onload = script.onreadystatechange = (function() {\n" +
            "if (!done && (!this.readyState || this.readyState == 'loaded'\n" +
            "|| this.readyState == 'complete')) {\n" +
            "done = true;\n" +
            "script.onload = script.onreadystatechange = null;\n" +
            "head.removeChild(script);\n" +
            "callback();\n" +
            "}\n" +
            "});\n" +
            "script.src = jqueryUrl;\n" +
            "head.appendChild(script);\n" +
            "}\n" +
            "else {\n" +
            "callback();\n" +
            "}\n" +
            "})(arguments[0], arguments[arguments.length - 1]);\n";
    return LoadJQuery;
}

Any help would be greatly appreciated, as I am having the same problems with other similar applications of JS Executor. Thank you!

Arran · Accepted Answer · 2013-07-02 21:07:04Z

1

Make the JavascriptExecutor instance local to that method.

JavascriptExecutor js = (JavascriptExecutor) driver;
// give jQuery time to load asynchronously
driver.manage().timeouts().setScriptTimeout(10, TimeUnit.SECONDS);
js.executeAsyncScript(jQueryLoader);

answered Jul 2, 2013 at 21:07

Arran

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1 Comment

kusold Over a year ago

That worked. Thanks so much! But do you happen to know why it requires a local instance?

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