Sometimes, we want to load vanilla JavaScript libraries into Node.js.

in this article, we’ll look at how to load vanilla JavaScript libraries into Node.js.

How to load vanilla JavaScript libraries into Node.js?

To load vanilla JavaScript libraries into Node.js, we can use readFileSync to read the JavaScript file.

Then we call the runInNewContext method from the vm module to run the script in a new context.

For instance, we write

execfile.js

const vm = require("vm");
const fs = require("fs");

module.exports = (path, context = {}) => {
  const data = fs.readFileSync(path);
  vm.runInNewContext(data, context, path);
  return context;
}

to create the execfile.js module, which exports a function that calls readFileSync with the script path.

Then we call vm.runInNextContext with the data, context, and path to run the script in the given context.

And then we return the context.

Then we require execfile.js in another module and call the exported function with

app.js

const execfile = require("./execfile");
const context = execfile("example.js", {
  someGlobal: 42
});
context.getSomeGlobal()

We call execfile with the 'example.js' and a context object that incorporate into the returned context.

And then we call context.getSomeGlobalto run the global function in theexample.js` script.

Conclusion

To load vanilla JavaScript libraries into Node.js, we can use readFileSync to read the JavaScript file.

Then we call the runInNewContext method from the vm module to run the script in a new context.