# Using Pyodide from Javascript
This document describes using Pyodide directly from Javascript. For information
about using Pyodide from Iodide, see [Using Pyodide from
Iodide](using_pyodide_from_iodide.md).
## Startup
To include Pyodide in your project you can use the following CDN URL,
https://pyodide-cdn2.iodide.io/v0.15.0/full/pyodide.js
You can also download a release from
[Github releases](https://github.com/iodide-project/pyodide/releases)
(or build it yourself), include its contents in your distribution, and import
the `pyodide.js` file there from a `
Pyodide test page
Open your browser console to see pyodide output
```
## Loading packages
Only the Python standard library and `six` are available after importing
Pyodide. To use other libraries, you'll need to load their package using
`pyodide.loadPackage`. This downloads the file data over the network (as a
`.data` and `.js` index file) and installs the files in the virtual filesystem.
Packages can be loaded by name, for those included in the official pyodide
repository (e.g. `pyodide.loadPackage('numpy')`). It is also possible to load
packages from custom URLs (e.g.
`pyodide.loadPackage('https://foo/bar/numpy.js')`), in which case the URL must
end with `.js`.
When you request a package from the official repository, all of that package's
dependencies are also loaded. Dependency resolution is not yet implemented
when loading packages from custom URLs.
Multiple packages can also be loaded in a single call,
```js
pyodide.loadPackage(['cycler', 'pytz'])
```
`pyodide.loadPackage` returns a `Promise`.
```javascript
pyodide.loadPackage('matplotlib').then(() => {
// matplotlib is now available
});
```
## Serving pyodide files
If you built your pyodide distribution or downloaded the release tarball
you need to serve pyodide files with a appropriate headers.
Because browsers require WebAssembly files to have mimetype of
`application/wasm` we're unable to serve our files using Python's built-in
`SimpleHTTPServer` module.
Let's wrap Python's Simple HTTP Server and provide the appropiate mimetype for
WebAssembly files into a `pyodide_server.py` file (in the `pyodide_local`
directory):
```python
import sys
import socketserver
from http.server import SimpleHTTPRequestHandler
class Handler(SimpleHTTPRequestHandler):
def end_headers(self):
# Enable Cross-Origin Resource Sharing (CORS)
self.send_header('Access-Control-Allow-Origin', '*')
super().end_headers()
if sys.version_info < (3, 7, 5):
# Fix for WASM MIME type for older Python versions
Handler.extensions_map['.wasm'] = 'application/wasm'
if __name__ == '__main__':
port = 8000
with socketserver.TCPServer(("", port), Handler) as httpd:
print("Serving at: http://127.0.0.1:{}".format(port))
httpd.serve_forever()
```
Let's test it out.
In your favourite shell, let's start our WebAssembly aware web server:
```bash
python pyodide_server.py
```
Point your WebAssembly aware browser to
[http://localhost:8000/index.html](http://localhost:8000/index.html) and open
your browser console to see the output from python via pyodide!