file_ get_ Contents() JSON after reading_ Decode cannot be converted to array

#1. Check the source code if any html The code can be used htmlspecialchars( character string ) or strip_tags( character string ) Remove html Mark 
#2. Check the source code if there is no html Code , But it can't be converted into an array , That's containing bom Head （$data Is the read string ）
   
 # Remove BOM head 
   $BOM = chr(239).chr(187).chr(191); 
   $data=str_replace($BOM,'',$data); 
   $data=json_decode($data,true);