Monkey-patches for filesystem related things. Rewrite require
function,
load Node's modules from memory. Or rewrite the whole fs
filesystem module.
Terms
An fs-like object is an object that implements methods of Node's
filesystem API.
It is denoted as vol
:
let vol = {
readFile: () => { /* ... */ },
readFileSync: () => { /* ... */ },
// etc...
}
fs-monkey
API
patchFs(vol[, fs])
- rewrites Node's filesystem modulefs
with fs-like objectvol
patchRequire(vol[, Module])
- rewritesrequire
function, patches Node'smodule
module to use a give fs-like objectvol
for module loading
Rewrites Node's filesystem module fs
with fs-like object.
vol
- fs-like objectfs
(optional) - a filesystem to patch, defaults torequire('fs')
import {patchFs} from 'fs-monkey';
const myfs = {
readFileSync: () => 'hello world',
};
patchFs(myfs);
console.log(require('fs').readFileSync('/foo/bar')); // hello world
You don't need to create fs-like objects yourself, use memfs
to create a virtual filesystem for you:
import {vol} from 'memfs';
import {patchFs} from 'fs-monkey';
vol.fromJSON({'/dir/foo': 'bar'});
patchFs(vol);
console.log(require('fs').readdirSync('/')); // [ 'dir' ]
Patches Node's module
module to use a given fs-like object vol
for module loading.
vol
- fs-like objectunixifyPaths
(optional) - whether to convert Windows paths to unix style paths, defaults tofalse
.Module
(optional) - a module to patch, defaults torequire('module')
Monkey-patches the require
function in Node, this way you can make
Node.js to require modules from your custom filesystem.
It expects an object with three filesystem methods implemented that are
needed for the require
function to work.
let vol = {
readFileSync: () => {},
realpathSync: () => {},
statSync: () => {},
};
If you want to make Node.js to require your files from memory, you
don't need to implement those functions yourself, just use the
memfs
package:
import {vol} from 'memfs';
import {patchRequire} from 'fs-monkey';
vol.fromJSON({'/foo/bar.js': 'console.log("obi trice");'});
patchRequire(vol);
require('/foo/bar'); // obi trice
Now the require
function will only load the files from the vol
file
system, but not from the actual filesystem on the disk.
If you want the require
function to load modules from both file
systems, use the unionfs
package
to combine both filesystems into a union:
import {vol} from 'memfs';
import {patchRequire} from 'fs-monkey';
import {ufs} from 'unionfs';
import * as fs from 'fs';
vol.fromJSON({'/foo/bar.js': 'console.log("obi trice");'});
ufs
.use(vol)
.use(fs);
patchRequire(ufs);
require('/foo/bar.js'); // obi trice
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