'TypeError: is not a function' in Node.js

Question

I'm getting the error while running the following code in Node.js

var assert = require('assert'); var request = require('request'); var index = require('./index'); it('verify javascript function', function(done) {     var v2 = index.AddNumbers(5, 6);     assert.equal(11, v2);     done(); }); 

The index.js file contain the following code:

function AddNumbers(a,b){     return a+b; } 

What am I doing wrong?

Answer 1

This happened to me many times because of circular dependency, check if you have 2 classes that are requiring each other, remove one of them from requiring the other and the issue should be solved

Answer 2

With NodeJS modules, to make something public, you have to export it. Add this to the end of index.js:

module.exports.AddNumbers = AddNumbers; 

(That's using the old CommonJS modules. For ESM, it would be export AddNumbers;)

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Here it is running on my machine:

 $ cat index.js  function AddNumbers(a,b){     return a+b; }  module.exports.AddNumbers = AddNumbers;  $ cat example.js  var index = require('./index'); var v2 = index.AddNumbers(5,6); console.log(v2);  $ node example.js 11