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This is probably the closest you can currently get to require something in node.js with completely bypassing the require cache.
stealthy-require
works like this:
The restrictions are:
This means you should have a close look at all internal require calls before you decide to use this library.
This is a module for node.js and is installed via npm:
npm install stealthy-require --save
Let's say you want to bypass the require cache for this require call:
var request = require('request');
With stealthy-require
you can do that like this:
var stealthyRequire = require('stealthy-require');
var requestFresh = stealthyRequire(require.cache, function () {
return require('request');
});
The require cache is bypassed for the module you require (i.e. request
) as well as all modules the module requires (i.e. http
and many more).
Sometimes the require cache shall not be bypassed for specific modules. E.g. request
is required but tough-cookie
– on which request
depends on – shall be required using the regular cache. For that you can pass two extra arguments to stealthyRequire(...)
:
module
variablevar stealthyRequire = require('stealthy-require');
var requestFresh = stealthyRequire(require.cache, function () {
return require('request');
},
function () {
require('tough-cookie'); // No return needed
// You can require multiple modules here
}, module);
require.cache
. However, as of browserify@13.0.1
the cache is passed as the 6th argument to CommonJS modules. Thus you can pass this argument instead:// Tweak for Browserify - using arguments[5] instead of require.cache
var requestFresh = stealthyRequire(arguments[5], function () {
return require('request');
});
If you are using stealthy-require
in node.js and repeatedly require fresh module instances the module.children
array will hold all module instances which prevents unneeded instances to be garbage collected.
Assume your code calls doSomething()
repeatedly.
var stealthyRequire = require('stealthy-require');
function doSomething() {
var freshInstance = stealthyRequire(require.cache, function () {
return require('some-module');
});
return freshInstance.calc();
}
After doSomething()
returns freshInstance
is not used anymore but won’t be garbage collected because module.children
still holds a reference. The solution is to truncate module.children
accordingly:
var stealthyRequire = require('stealthy-require');
function doSomething() {
var initialChildren = module.children.slice(); // Creates a shallow copy of the array
var freshInstance = stealthyRequire(require.cache, function () {
return require('some-module');
});
module.children = initialChildren;
return freshInstance.calc();
}
The slice
operation removes all new module.children
entries created during the stealthyRequire(...)
call and thus freshInstance
gets garbage collected after doSomething()
returns.
// 1. Load stealthy-require
var stealthyRequire = require('stealthy-require');
// This does nothing but loading the code.
// It has no side-effects like patching the module loader or anything.
// Any regular require works as always.
var request1 = require('request');
// 2. Call stealthyRequire with passing the require cache and a callback.
var requestFresh = stealthyRequire(require.cache, function () {
// 2a. Before this callback gets called the require cache is cleared.
// 2b. Any require taking place here takes place on a clean require cache.
// Since the require call is part of the user's code it also works with module bundlers.
return require('request');
// Anything returned here will be returned by stealthyRequire(...).
// 2c. After this callback gets called the require cache is
// - cleared again and
// - restored to its old state before step 2.
});
// Any regular require again works as always.
// In this case require returns the cached request module instance.
var request2 = require('request');
// And voilà:
request1 === request2 // -> true
request1 === requestFresh // -> false
To set up your development environment for stealthy-require
:
cd
to the main folder,npm install
,npm install gulp -g
if you haven't installed gulp globally yet, andgulp dev
. (Or run node ./node_modules/.bin/gulp dev
if you don't want to install gulp globally.)gulp dev
watches all source files and if you save some changes it will lint the code and execute all tests. The test coverage report can be viewed from ./coverage/lcov-report/index.html
.
If you want to debug a test you should use gulp test-without-coverage
to run all tests without obscuring the code by the test coverage instrumentation.
In case you never heard about the ISC license it is functionally equivalent to the MIT license.
See the LICENSE file for details.