Run javascript on HTML generated from C# string

Question

I would like to run javascript on HTML generated from C# string. (without opening browser - just C# code)

Something like:

string myHTML = '<div id="divTest">This is test<br/><br/></div>';

Javascript should be:

function test 
{
     return document.getElementById('divTest').offsetHeight;
}

What I've already tried is check some headless browsers like PhantomJS and Optimus - but they don't have an option to render string (only to open web page through web address like http://google.com/. Is there a way to achieve this through C#?

Are you appending string myHTML to your page HTML. This should be accessible from any browser. — Amit Kumar Singh
– Amit Kumar Singh, Commented Aug 30, 2017 at 15:12
if the html is placed in dom as html, it should be accessible — Koushik Chatterjee
– Koushik Chatterjee, Commented Aug 30, 2017 at 15:15
This is not entirely clear. You want to run javascript on a string of HTML, and get the height of the element.... outside a browser, i.e. in something like a command-line tool etc? — adeneo
– adeneo, Commented Aug 30, 2017 at 15:17
but they don't have an option to render string - what do you mean by this? — Lloyd
– Lloyd, Commented Aug 30, 2017 at 15:25

Isma · Accepted Answer · 2017-08-30 16:04:09Z

1

The following is working for me:

string html = "<html><head></head><body><div id=\"divTest\">This is test<br/><br/></div></body></html>";

string script1 = "return document.getElementById('divTest').innerText";
string script2 = "return document.getElementById('divTest').offsetHeight";

var options = new PhantomJSOptions();
options.AddAdditionalCapability("javascriptEnabled", true);

var driver = new PhantomJSDriver(options);
driver.Url = "file://dummy.html";
driver.Navigate();
driver.ExecutePhantomJS("document.write('" + html + "');");

var test1 = driver.ExecutePhantomJS(script1);
//Returns: This is a test
var test2 = driver.ExecutePhantomJS(script2);
//Returns: 40

You need to install the Selenium.WebDriver NuGet and to download the PhantomJS exe from http://phantomjs.org/download.html it needs to be in the same folder as your exe or in the PATH.

edited Aug 30, 2017 at 16:04

answered Aug 30, 2017 at 15:22

Isma

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5 Comments

FrenkyB Over a year ago

I would like to run javascript without opening browser. Just C# code.

FrenkyB Over a year ago

Do you have any example on this? Or link?

Isma Over a year ago

I added an example, haven't tested it myself but should work or at least get you in the right direction ;-)

Isma Over a year ago

I managed to make it work with a few tweaks, I edited the answer.

FrenkyB Over a year ago

Your solution is good. The only thing which I don't know is how to set global variable for driver in MVC? I want to open PhantomJSDriver and keep it open (because this is much faster than open - close each time). It's not a problem to do this in windows application, but what about MVC?

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