Add or Repalce Text in PHP

I am new In PHP.I have js file look like

   var sites = [
  //Texte anime
   {url:" http://carouselinfo.com/canal/", duration:9},
  //Texte anime
   {url:" http://carouselinfo.com/canal-2/", duration:9}, 
   //Intro detallee
  {url:"http://carouselinfo.com/index-t1.html", duration:35},
  //CTA
  {url:"http://carouselinfo.com/index-t2.html", duration:35},
 
  //Football
   {url:"http://carouselinfo.com/twitter-ligue/", duration:100},
 
 
  //Texte anime
   {url:" http://carouselinfo.com/canal-2/", duration:9}, 
 
   //TrailersClub.com
   {url:"http://trailersclub.com/?lang=fr", duration:480},
 
  //Heure
  {url:"http://carouselinfo.com/heure", duration:8},
  //Meteo
  {url:"http://carouselinfo.com/meteo", duration:12},
  //Texte anime
   {url:" http://carouselinfo.com/canal-cine/", duration:9},
  //Cine
  {url:"http://carouselinfo.com/cine/index-t1.html", duration:150},
   //Texte anime
   {url:" http://carouselinfo.com/canal-2/", duration:9}, 
  //Heure
  {url:"http://carouselinfo.com/heure", duration:8},
    ];
 

I want to add text after var site=[ or any line say at 4 lines using php so how can we add.Here is my code of replacing Text on any line.

$lines = array();
 foreach( file('source.js') as $line ) {
   if ( 'var site=[' === $line ) {
     array_push($lines, 'test');
   }
   array_push($lines, $line);
 }
 
 file_put_contents('source.js', $lines);
 

This code is not working out.

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