type void is not assignable to array

Question

I am trying to create a method that removes all the zeros from a string (a string that contains numbers) for each element of an array;

I get this error 'type void is not assignable to programs[]

 public removeLeadingZeros(programs: Program[]) {
    let programCopy: Program[];
    programCopy= programs.forEach(p => {
      p.number.replace(/^0+/, '');
    });

    return programCopy;
  }

Answer 1

As an alternative to the other answer, instead of using .forEach() which doesn't return anything, you can use the .map() which returns an array of what you have changed.

let programCopy: Program[];
programCopy = programs.map(p => {
  p.number.replace(/^0+/, '');
  return p;
});

EDIT: Here is the shorter version of this code

let programCopy: Program[] = programs.map(p => p.number.replace(/^0+/, ''));

Answer 2

Thats because forEach does not have any return type.

if you want to store the objects with the replaced numbers in programCopy just copy the programs parameter and change them:

programCopy = programs;
programCopy.forEach(p => {
  p.number.replace(/^0+/, '');
});

Answer 3

Use the following instead of forEach loop:

programCopy = programs.filter(p => p !== 0);

You can use filter method. It returns an array of the filtered items. Now, the programCopy variable contains the number without zeros.

Answer 4

You can use this approach.

 public removeLeadingZeros(programs: Program[]) { let programCopy: Program[]; programs.forEach(p => { programCopy.push(p.number.replace(/^0+/, '')) }); return programCopy; }