Getting started

To get started with Cheerp, you’ll first need to install it. Or, you can try Cheerp without installing it with Cheerp playground.

Cheerp in itself has no dependencies, but the recommended workflow and the tutorials make use of:

  • a JavaScript engine (such as Node.js)
  • an HTTP server (such as http-server)
  • a web browser

If you don’t have these, see recommended workflow.

Compiling your first application

You are now ready for compiling your first Web application using Cheerp. Move to a folder of your choice and save the following C++ program as hello.cpp.

// The cheerp/clientlib.h header contains declarations for the browser APIs
#include <cheerp/clientlib.h>
// webMain is the entry point for web applications written in Cheerp
void webMain()
client::console.log("Hello, World Wide Web!");

You can then compile this program using the following command line:

Terminal window
/opt/cheerp/bin/clang++ -target cheerp hello.cpp -o hello.js

Great, you have compiled your first program with Cheerp. You can now run the generated JavaScript directly with

Terminal window
node hello.js

You can also save this HTML file as hello.html:

<!doctype html>
<html lang="en">
<meta charset="utf-8" />
<title>Cheerp example 0: hello</title>
<script defer src="hello.js"></script>
<h1 id="pagetitle">
Open the console log (Ctrl + Shift + J or Ctrl + Option + J) to read the

and from the same folder firefox hello.html (or equivalent).

This is what the result should look like: hello.html

Why webMain() instead of main()?

What is console.log()?

It would have compiled also with std::cout<< , printf() or int main() (try it yourself), but we wanted to show first what zero-overhead access to the browser looks like.