How to get element details from script tag using JavaScript in selenium webdriver?

Question

There is a canvas element on this page which is an image having a number which changes whenever you refresh page or do anything on the page which requires reloading.

In the source code what I see is only this:

<div class="row">
      <div class="large-10 columns">
        <canvas id="canvas" width="599" height="200" style="border:1px dotted;"></canvas>
      </div>
    </div>

So in-short there is nothing I can do with this info on the outer html but when I went to network section and saw the response code in which I found this code which uses javascript:

    <script>var canvas_el = document.getElementById('canvas');
var canvas = canvas_el.getContext('2d');
canvas.font = '60px Arial';
canvas.strokeText('Answer: 19403',90,112);
</script>

Now my problem is how can I write javascript(I don't know that much of javascript) in selenium webdriver to get this details(Specifically strokeText) under the script tag which are otherwise not there on the source code. I am looking for some solution using JavascriptExecutor.

Just in case you are wondering what I have tried. I came across this answer: stackoverflow.com/questions/14904378/… But in this case they are getting the data attributes which are linked to script tag itself unlike here where I want to get attributes which are inside of script tag. — MohitChouhan
– MohitChouhan, Commented May 10, 2018 at 15:07

Parabolord · Accepted Answer · 2018-05-10 21:08:31Z

1

You had the right idea with using JavascriptExecutor. I found the basic strategy here.

final By SCRIPT = By.tagName("script");

List<WebElement> scripts = new WebDriverWait(driver, 5)
        .until(ExpectedConditions.presenceOfAllElementsLocatedBy(SCRIPT));

JavascriptExecutor js = (JavascriptExecutor) driver;
String query = "return document.getElementsByTagName(\"script\")[arguments[0]].innerHTML;";     
Pattern p = Pattern.compile("canvas.strokeText\\('Answer: \\d+'");
Pattern p2 = Pattern.compile("\\d+");

String number = IntStream.range(0, scripts.size())
        .mapToObj(i -> (String)js.executeScript(query, i))
        .map(string -> p.matcher(string))
        .filter(m -> m.find())
        .map(m -> p2.matcher(m.group()))
        .filter(m -> m.find())
        .map(m -> m.group())
        .findFirst()
        .orElse(null);
System.out.println(number);  // prints the number rendered on the page

edited May 10, 2018 at 21:08

answered May 10, 2018 at 21:00

Parabolord

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2 Comments

MohitChouhan Over a year ago

It works! but I have a query here what is that 'arguments[0]'. Does that mean you are getting the first script tag of all script tags present in the source code?

Parabolord Over a year ago

It's a way to supply arguments to the javascript script. Try this: js.executeScript("alert(arguments[0])", "Mohit", "Chouhan"); and then this: js.executeScript("alert(arguments[1])", "Mohit", "Chouhan");. Explained here

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