Is it possible to iterate and replace values in an array using forEach?

Question

I want to iterate an array of strings and replace each element with another string:

let arr = ["-","-","-"]

let spaceArr = replaceStringArr.forEach(replaceDash)

const replaceDash = function(index:any, array:any){
   // replace the value of each element containing "-" with "&nbsp"
   I have tried 
   return array[index] = "&nbsp"
   and
   array[index] = "&nbsp"
}

I have tried:

const replaceDash = function(index: any, array: any) {
  return array[index] = "&nbsp"
}

as well as:

const replaceDash = function(index: any, array: any) {
  array[index] = "&nbsp"
}

But I am getting a:

TypeError: Cannot create property '-' on number '0'

Answer 1

forEach receives the parameter currentValue first, index second, array third. You would need to modify the function as follows:

const replaceDash = function(item:any, index:any, array:any){
   // replace the value of each element containing "-" with "&nbsp"
   if(item === "-") array[index] = "&nbsp";
}

If I were you I'd also take a look at map function, which will give you a new array and seems to be more suited to what you want in less code:

let spaceArr = replaceStringArr.map(item => item === '-' ? '&nbsp' : item);

Answer 2

It seems you are misunderstanding for .forEach works and confusing it for .map.

.forEach just iterates through an array, it doesn't return anything, while .map actually returns the new modified array. If you want spaceArr to be the array with modified values, try this:

let arr = ["-","-","-"]

let spaceArr = arr.map(value => {return "&nbsp"})