This is a exercise to do with Javascript.

reduce.js

[
  { id: 1, likes: 13, text: 'Lets code in Reactjs for all day long!' },
  { id: 2, likes: 87, text: 'Software Developer is a good choice to your life!' },
  { id: 3, likes: 51, text: 'Make your code readability.' },
  { id: 4, likes: 32, text: 'Open Source Software is the best thing for the developers learn more and more.' },
]
// -> Remove the likes property ->
[
  { id: 1, text: 'Lets code in Reactjs for all day long!' },
  { id: 2, text: 'Software Developer is a good choice to your life!' },
  { id: 3, text: 'Make your code readability.' },
  { id: 4, text: 'Open Source Software is the best thing for the developers learn more and more.'},
]

Note: if you care about not mutating data, you might consider using Object.assign({}, rules, { [field.name]: field.constraints }) or using the object spread syntax, { ...rules, [field.name]: field.constraints }. I would advise against this. Personally, I’m a firm believer in the value of immutable data, but with pragmatism. In this case, a new object will be created for each iteration which could end up using quite a lot of unnecessary memory in your app