When the dialog window opens, look for the "JavaScript" section and select "Allow all sites to run JavaScript (recommended)". The tag, it knows it’s reached the end of the JavaScript program and can get back to its normal duties. You also asked: And if I write the code in C++, then how to use the js API-s. Again, you're kind of missing the point. Let’s understand in following sections, how the JavaScript code embeds inside an HTML file: The