Differences between IE and firefox in jquery usage _ jquery

Jquery users often need to test firefox compatibility. IE and Firefox can run.
// Handle the carriage return event
$ (Document). keydown (function (event ){
If (event. keyCode = 13 ){
Alert ($ ('# idone'). val ());
// Press enter to obtain ISBN
If ($ ('# idone'). val () = 'isbn '){
// Isbncheck ();
$ ('# Ztm'). focus ();
} Else
If ($ ('# idone'). val () = 'ztm '){
$ ('# Bltm'). focus ();
}
If ($ ('# idone'). val () = 'bltm '){
$ ('# Ftm'). focus ();
} Else
If ($ ('# idone'). val () = 'ftm '){
$ ('# Dyzrsm'). focus ();
}

}
});

Only IE can run.
// Handle the carriage return event
$ (Document). keydown (function (){
If (event. keyCode = 13 ){
// Alert ($ ('# idone'). val ());
// Press enter to obtain ISBN
If ($ ('# idone'). val () = 'isbn '){
// Isbncheck ();
$ ('# Ztm'). focus ();
}
If ($ ('# idone'). val () = 'ztm '){
$ ('# Bltm'). focus ();
}
If ($ ('# idone'). val () = 'bltm '){
$ ('# Ftm'). focus ();
}
}
});
In summary, debugging programs under Firefox is conducive to program compatibility.