JScript replaceInFile

function replaceInFile( filename , searchForRx , replaceWith )
{
  filename = FormatArguments(filename , arguments); 
  
  if(typeof (searchForRx) == "string")
    searchForRx = FormatArguments(searchForRx , arguments); 
 
  replaceWith = FormatArguments( replaceWith , arguments ); 
 
  var text = ReadAll(filename); 
   // if(!searchForRx.exec(text) ) 
  
  text = text.replace(searchForRx,replaceWith); 
  
  WriteAll(filename, text); 
}