TypeError: cannot read properties of undefined (reading 'substring') in node js

Question

I am trying to get a part of a string.

let someValue = 'basic jkclwkjkvhrvhkuirhiehvyrbuyrbevnervnhrev';
let getSubstringValue = someValue.substring(6);

But, in my node JS server gives,

TypeError: Cannot read properties of undefined (reading 'substring')

Also used 'substr' using ' this answer '. But it also gave this 'TypeError: Cannot read properties of undefined (reading 'substr')' error.

Answer 1

Can you debug someValue if it is a string?
If it's undefined , you get the error
TypeError: Cannot read properties of undefined

Simple example of substring:

exampleVal = 'test';

// remove the first character
exampleVal = exampleVal.substring(1);

// show results (output is 'est')
console.log(exampleVal);

// example for if exampleVal is undefined

let exampleVar = undefined;
exampleVar = exampleVar.substring(1);
console.log(exampleVar);

// error is thrown 
// TypeError: Cannot read properties of undefined (reading 'substring')