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node-internal-modules-cjs-helpers.js
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node-internal-modules-cjs-helpers.js
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const {ArrayPrototypeForEach, StringPrototypeStartsWith, ObjectPrototypeHasOwnProperty, StringPrototypeIncludes, ObjectDefineProperty} = require('./node-primordials');
exports.addBuiltinLibsToObject = addBuiltinLibsToObject;
// Copied from https://github.com/nodejs/node/blob/21f5a56914a3b24ad77535ef369b93c6b1c11d18/lib/internal/modules/cjs/helpers.js#L133-L178
function addBuiltinLibsToObject(object) {
// Make built-in modules available directly (loaded lazily).
const { builtinModules } = require('module').Module;
ArrayPrototypeForEach(builtinModules, (name) => {
// Neither add underscored modules, nor ones that contain slashes (e.g.,
// 'fs/promises') or ones that are already defined.
if (StringPrototypeStartsWith(name, '_') ||
StringPrototypeIncludes(name, '/') ||
ObjectPrototypeHasOwnProperty(object, name)) {
return;
}
// Goals of this mechanism are:
// - Lazy loading of built-in modules
// - Having all built-in modules available as non-enumerable properties
// - Allowing the user to re-assign these variables as if there were no
// pre-existing globals with the same name.
const setReal = (val) => {
// Deleting the property before re-assigning it disables the
// getter/setter mechanism.
delete object[name];
object[name] = val;
};
ObjectDefineProperty(object, name, {
get: () => {
const lib = require(name);
// Disable the current getter/setter and set up a new
// non-enumerable property.
delete object[name];
ObjectDefineProperty(object, name, {
get: () => lib,
set: setReal,
configurable: true,
enumerable: false
});
return lib;
},
set: setReal,
configurable: true,
enumerable: false
});
});
}