use an external js library in a node-red function

问题:

I've installed a js library https://www.npmjs.com/package/fft with npm, how can I make this available in node-red functions ?

回答1:

This is covered towards the end of the Configuration and the Writing Functions sections of the Node-RED docs

You need to add npm modules to the settings.js file. You can find this file in ~/.node-red/

The section you are looking for is the functionGlobalContext section.

...
functionGlobalContext: {
   fft: require('fft')
},
...

You would then access the module in the function node with the following:

var FFT = context.global.get('fft');
var fft = new FFT(n, inverse);
...

Also be careful where you installed the fft module, it needs to be either in ~/.node-red/node_modules or installed globally so it is accessable to Node-RED