Problem #1

When you want to replace one word with another, you have to do the following actions:

1. Copy a word or some text
2. Turn on the VISUAL_MODE by pressing v
3. Select a word or text that you want to replace
4. Hit p to replace the word

After you press p, your default register will be overridden.
Which is not what you usually want.

Let's consider the real-case scenario. You have the following code:

const hello = 'Hello World.';
const hi = 'Hi Word.';

You want to replace Word with World. Your cursor is at line one at the first character.

1. fW - go to the word World
2. yiw - copy the word
3. j - go down
4. FW - go to the word Word
5. v - enter the VISUAL_MODE
6. e - select the full word
7. p - paste previously copied word

Problem #2

Another problem is when you want to replace multiple places with the same word.

We have:

const hello = 'Hello World.';
const hi = 'Hi Word.';
const greetings = 'Greetings Word.';

1. fW - go to the word World
2. yiw - copy the word
3. j - go down
4. FW - go to the word Word
5. v - enter the VISUAL_MODE
6. e - select the full word
7. p - paste previously copied word

And now, you need to replace the word Word with the word World, but your register was overwritten with the word Word. So you need to copy it again.

8. yiw - copy the word World at the place where you are
9. j - go down
10. fW - go to the word World
11. v - enter the VISUAL_MODE
12. e - select the full word
13. p - paste previously copied word

A lot of extra work, right?

Instead, you can use the an alternative register. For example, to copy to register a you need to press "ayiw, and to paste instead of the word you want to replace you need to press "ap (ve"ap).

But it looks like a long sequence of keys to press.

Solution #1

We can implement our own operator, which will help with the substitution. The current operator works with motions as well.

nnoremap <expr> x SpecialChange()

function! SpecialChange(type = '')
  if a:type == ''
      set opfunc=SpecialChange
      return 'g@'
  endif
  execute 'normal! `[v`]"_d"' .. v:register .. 'P'
endfunction

So, the formula is {operator}{motion}.

Let's try to solve Problem #1 with this operator.

1. fW - go to the word World
2. yiw - copy the word
3. j - go down
4. FW - go to the word Word

From this point, we don't need to select the word, as we can replace it by simply using the motion:

5. xiw - replace the current word (Word) with World by using the previously implemented custom operator

Now, let's try to solve Problem #2:

1. fW - go to the word World
2. yiw - copy the word
3. j - go down
4. FW - go to the word Word
5. xiw - replace Word with the word World

Our operator gives us the ability to replace the word without overriding the word that copied to the default register.

7. j - go down
8. fW - go to the word World
9. xiw - replace the current word (Word) with World by using the previously implemented custom operator

Solution #2

There is a plugin called vim-subversive.

It can do everything described in Solution #1 and much more.

Summary

If you hesitate and don't know what to choose, I recommend installing and playing with the plugin. After some time, if you realize you're using a single feature from the plugin, you can switch to the operator we wrote above. Personally, I use a custom operator as it covers all my needs.