In node.JS how can I get the path of a module I have loaded via require that is *not* mine (i.e. in some node_module)

If I correctly understand your question, you should use require.resolve():

Use the internal require() machinery to look up the location of a module, but rather than loading the module, just return the resolved filename.

Example: var pathToModule = require.resolve('module');


require.resolve() is a partial answer. The accepted answer may work for many node modules, but won't work for all of them.

require.resolve("moduleName") doesn't give you the directory where the module is installed; it gives you the location of the file defined in the main attribute in the module's package.json.

That might be moduleName/index.js or it could be moduleName/lib/moduleName.js. In the latter case, path.dirname(require.resolve("moduleName")) will return a directory you may not want or expect: node_modules/moduleName/lib

The correct way to get the complete path to a specific module is by resolving the filename:

let readmePath = require.resolve("moduleName/README.md");

If you just want the directory for the module (maybe you're going to make a lot of path.join() calls), then resolve the package.json — which must always be in the root of the project — and pass to path.dirname():

let packagePath = path.dirname(require.resolve("moduleName/package.json"));

FYI, require.resolve returns the module identifier according to CommonJS. In node.js this is the filename. In webpack this is a number.

In webpack situation, here is my solution to find out the module path:

const pathToModule = require.resolve('module/to/require');
console.log('pathToModule is', pathToModule); // a number, eg. 8
console.log('__webpack_modules__[pathToModule] is', __webpack_modules__[pathToModule]);

Then from __webpack_modules__[pathToModule] I got information like this:

(function(module, exports, __webpack_require__) {

    eval("module.exports = (__webpack_require__(6))(85);\n\n//////////////////\n// 
    WEBPACK FOOTER\n// delegated ./node_modules/echarts/lib/echarts.js from dll-reference vendor_da75d351571a5de37e2e\n// module id = 8\n// module chunks = 0\n\n//# sourceURL=webpack:///delegated_./node_modules/echarts/lib/echarts.js_from_dll-reference_vendor_da75d351571a5de37e2e?");

    /***/
})

Turned out I required old scripts from previous dll build file(for faster build speed), so that my updated module file didn't work as I expected. Finally I rebuilt my dll file and solved my problem.

Ref: Using require.resolve to get resolved file path (node)

Tags:

Node.Js

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