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Using Pyodide from Javascript
This document describes using Pyodide directly from Javascript. For information about using Pyodide from Iodide, see Using Pyodide from Iodide.
Startup
Include pyodide.js in your project.
This has a single Promise object which bootstraps the Python environment:
languagePluginLoader. Since this must happen asynchronously, it is a
Promise, which you must call then on to complete initialization. When the
promise resolves, pyodide will have installed a namespace in global scope:
pyodide.
languagePluginLoader.then(() => {
// pyodide is now ready to use...
console.log(pyodide.runPython('import sys\nsys.version'));
});
Running Python code
Python code is run using the pyodide.runPython function. It takes as input a
string of Python code. If the code ends in an expression, it returns the result
of the expression, converted to Javascript objects (See type
conversions).
pyodide.runPython('import sys\nsys.version'));
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 <package-name>.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,
pyodide.loadPackage(['cycler', 'pytz'])
pyodide.loadPackage returns a Promise.
pyodide.loadPackage('matplotlib').then(() => {
// matplotlib is not available
});
Complete example
TODO