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JavaScript Node.js Basics 2017 Handling Errors in Node Organizing Your Code with require

Posted by Cheryl Chao
Cheryl Chao
5,555 Points

Why TypeError: undefined is not a function

I simply cut my getProfile function and paste in the new profile.js file ->rename the function name as get as my code is const profile = require('./profile.js');

const users = process.argv.slice(2); users.forEach(profile.get);

the console shows treehouse:~/workspace$ node app.js chalkers
/home/treehouse/workspace/app.js:8
users.forEach(profile.get);
^

TypeError: undefined is not a function
at Array.forEach (<anonymous>)
at Object.<anonymous> (/home/treehouse/workspace/app.js:8:7)
at Module._compile (module.js:653:30)
at Object.Module._extensions..js (module.js:664:10)
at Module.load (module.js:566:32)
at tryModuleLoad (module.js:506:12)
at Function.Module._load (module.js:498:3)
at Function.Module.runMain (module.js:694:10)
at startup (bootstrap_node.js:204:16)
at bootstrap_node.js:625:3

1 Answer

Martin Balon
Martin Balon
43,651 Points
Martin Balon
Martin Balon
43,651 Points

Hi Cheryl,

it seems that you forgot to export the function/object from profile.js. In profile.js you have to use module.exports and select a function/object/array etc that you want to export.

Also if you named your function 'get' in profile.js and exported only this function then you would call the function using name 'profile'. If on the other hand you had and object which contains method named 'get' and exported this object then to call the function you would use profile.get().

For more details and example follow the link below. https://stackify.com/node-js-module-exports/#:~:text=Module%20exports%20are%20the%20instruction,To%20understand%20modules%20in%20Node.