Regex to find arrow functions with default value

regex.js

const regEx = /\(.*(=+).*\) =>/;
// saved regex with examples: https://regex101.com/r/DcCtwT/1

// this will match the functions of this type: 
const ArrowWithDefault = (argument = {whatever: 'abcdef'}) => {
  return argument.whatever;
}
// NB: it won't match if the parenthesis are missing, or if the space before the arrow is missing

// the following will not match
const WontMatch = (argument = {whatever: 'abcdef'})=> {
  return argument.whatever;
}