Example

105,109s/\([a-zA-Z]*\)\(:\)\(.*\)/\1\2'\1',/g

Before

payload: {
  companyName: string,
  companyGstNumber: string,
  companyEmail: string,
  companyPhoneNumber: string,
}

After

payload: {
  companyName:'companyName',
  companyGstNumber:'companyGstNumber',
  companyEmail:'companyEmail',
  companyPhoneNumber:'companyPhoneNumber',
}

See also: https://stackoverflow.com/questions/19902089/vim-regex-capture-groups-bau-byau-ceu-cyeu