怎么利用js读取txt文件

js读取txt文件：

function  readFile(filename){
var  fso =  new  ActiveXObject( "Scripting.FileSystemObject" );
var  f = fso.OpenTextFile(filename,1);
var  s =  "" ;
while  (!f.AtEndOfStream)
s += f.ReadLine()+ "\n" ;
f.Close();
return  s;
}

js写txt文件：

function  writeFile(filename,filecontent){
var  fso, f, s ;
fso =  new  ActiveXObject( "Scripting.FileSystemObject" );
f = fso.OpenTextFile(filename,8, true );
f.WriteLine(filecontent);
f.Close();
alert( 'ok' );
}