title: Regular expression: repeating patterns in the beginning of string
body: <p>For example, consider the following string: <code>"apple1: apple2: apple3: some random words here apple4:"</code></p>
  
  <p>I want to match only apple1, apple2 and apple3 but not apple4. I am having a hard time to figure out how to archive this. </p>
  
  <p>Any help is appreciated.</p>
  
  <p>Thanks.</p>