Unable to export a function from a custom node.js module

Question

I am testing out a simple node.js custom module represetned by the processTest.js file in the node.js root directory. Here is its contents: notice that the module.exports includes the one function processTest():

'use strict';

const { spawn } = require( 'child_process' );
const ls = spawn( 'ls', [ '-lh', '/usr' ] );

function runTest() {
  ls.stdout.on('data', (data) => {
    console.log(`stdout: ${data}`);
  });

  ls.stderr.on('data', (data) => {
    console.log(`stderr: ${data}`);
  });

  ls.on('close', (code) => {
    console.log(`child process exited with code ${code}`);
  });
}
module.exports = runTest;

In the main node.js script we try to invoke it as follows:

const processTest = require("./processTest")

...

http.createServer(app).listen(port, '0.0.0.0', function () {
  console.debug(`HTTP: Listening on ${port} ..`)
  processTest.runTest();
})

However we get the error

Uncaught TypeError: processTest.runTest is not a function

note that the processTest module is actually present and the function is visible.

What is wrong here and how should it be corrected?

processTest() did not work - I needed to change the module exports as shown in the [soon to be] accepted answer — WestCoastProjects
– WestCoastProjects, Commented Sep 15, 2021 at 0:21

pxDav · Accepted Answer · 2021-09-15 00:20:07Z

2

You are referring to the function in the processTest file. (module.exports = runTest). Use require("./processTest")()

Or just change the module.exports to

module.exports = {
    runTest
}

and require("./processTest").runTest() will work

edited Sep 15, 2021 at 0:20

answered Sep 15, 2021 at 0:17

pxDav

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1 Comment

Bergi Over a year ago

No reason to overwrite the export with a new object. It's much better to simply assign module.exports.runTest = runTest;

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