Concatenating a string in a forEach loop js

Question

I’m trying some tester code I turn a string into UpperCase Then split it to make it into an array and then loop through it using ES6 forEach loop However when I try to concatenate ‘hello’ to the subject of the loop It returns undefined

const string = 'abcd'
console.log(string.toUpperCase().split('').forEach(element => element += 'hello'))

And when I add join(‘’) to it it returns this

undefined is not an object (evaluating string.toLowerCase().split('').forEach(element => element +=('hello')).join')

forEach does not return anything accept its undefined default value. Please read some documentation ... forEach, map, reduce — Peter Seliger
– Peter Seliger, Commented Sep 19, 2021 at 7:58

Peter Seliger · Accepted Answer · 2021-09-19 08:05:46Z

2

You need to use map function to make any changes to array elements

const string = 'abcd';

console.log(
  string
    .toUpperCase()
    .split('')
    .map(char =>
      char += ' hello'
    ).join(', ')
);

edited Sep 19, 2021 at 8:05

Peter Seliger

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answered Sep 19, 2021 at 7:59

Prakash GPz

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Comments

Flash Thunder · Accepted Answer · 2021-09-19 08:08:29Z

0

map is the proper way to do it, but if you need to use forEach, use it like that:

const string = 'abcd'
var newstr = '';
string.toUpperCase().split('').forEach(element => newstr += element + 'hello');
console.log(newstr);

answered Sep 19, 2021 at 8:08

Flash Thunder

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