How to use mbstring on Heroku (PHP) code example

Example: How to use mbstring on Heroku (PHP)

Create Composer file in your app folder

project_dir:~$> touch composer.json

# add these lines in your composer.json
{
  "require": {
    "ext-mbstring": "*"
  }
}

#save composer file
#And heroku will automatically add the mbstring extension 
#to your app on the next deploy.