title: Remove All Unnecessary Whitespaces from JSON String (in PHP)
body: <p>How do I remove ALL <strong>unnecessary</strong> whitespaces from a JSON String (in PHP)?</p>
  
  <p>I assume that I need to use preg_replace with some clever regex in order to NOT touch the whitespaces that are part of the values.</p>
  
  <p><em>A simple example would be:</em></p>
  
  <p><strong>Before:</strong> '{ "key": "value with whitespaces to maintain" }'</p>
  
  <p><strong>After:</strong> '{"key":"value with whitespaces to maintain"}'</p>
  
  <p>Basically, I'm looking for a way to minify and pack the string as tight as possible without changing any data.</p>