Loading a javascript module stored on IPFS

Question

Let's say I have javascript files on IPFS, for example, this. I want to build a piece of javascript (node) code that will retrieve the ipfs hash, and will then have to load the file(s) pointed to. So far I'm doing:

node.get(fileHash, (err, files) => {
    // some check for error
    files
    .filter(file => file.type === 'file')
    .forEach(file => {
        vm.runInThisContext(
            code    = file.content.toString('utf8'),
            options = { filename: file.name }
        );
    });
});

I don't really want to mess up with the filesystem (this will have to run in a browser) so I'd like to avoid writing the files and then requiring them.

Is there a better way to load javascript code that is stored in a variable (basically). I feel like I'm using some sort of eval ... which I don't like

olizilla · Accepted Answer · 2019-08-27 08:54:53Z

You could load the modules from the IPFS HTTP Gateway

<script src="https://ipfs.io/ipfs/<cid>/mything.js" />

If the user has ipfs-companion installed, the resource will be fetched from the users local ipfs gateway at localhost:8080, and if not it will be fetched from the public gateway at ipfs.io. This could be interesting with es modules and import flavour

import foo from https://ipfs.io/ipfs/<cid>/index.js`

If you want to load the resources with js-ipfs as in your example, then you can use [ipfs.cat][2] to get the response instead of ipfs.get. You'll have to do some form of eval as you didnt ask the browser to fetch the script

// get the script
const data = await ipfs.cat('CidForYourScript')

// depending on how your script is packaged, eval it
const exports = (new Function(data.toString()))()

See this PR on js-ipfs for more discussion of this idea from the core developers: https://github.com/ipfs/js-ipfs/pull/1830

For more ideas on eval-ing js see: https://benclinkinbeard.com/posts/how-browserify-works/

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