title: Replace spaces with underscore only in tag
body: <p>data:  <code>&lt;product name_here&gt;Product A&lt;/product_name here&gt;</code></p>
  
  <p>I try this <code>$replace = preg_replace('/\s+/', '_', $replace);</code></p>
  
  <p>but it show incorrect like this : <code>&lt;product_name_here&gt;Product_A&lt;/product_name_here&gt;</code></p>
  
  <p>Just only replace space with underscore only inside tag name , no need to change space in value </p>
  
  <p>I want like this :  <code>&lt;product_name_here&gt;Product A&lt;/product_name_here&gt;</code></p>
  
  <p>Please help.</p>