Automatically Jumping To The Next Field
If your form contains data that is of a fixed length it may be convenient to have the cursor
automatically jump to the next field when the proper amount of data is filled in. For
example, a social security number consists of three fields of 3, 2, and 4 characters long.
We can set those three fields so that the cursor jumps automatically from one to the next
as the data is filled in.
First, copy this script exactly as-is into the <HEAD> section of your document.
var myForm=document.forms[document.forms.length - 1];
if (myField.maxLength == null)
(this == downStrokeField) &&
(this.value.length > this.beforeLength) &&
(this.value.length >= this.maxLength)
Now, suppose we have this form in which the first three fields represent the social
security number. We create the fields as usual without any special markup.
<FORM ACTION="../cgi-bin/mycgi.pl" METHOD=POST>
<INPUT TYPE=TEXT NAME="ssn_1" MAXLENGTH=3 SIZE=3> -
<INPUT TYPE=TEXT NAME="ssn_2" MAXLENGTH=2 SIZE=2> -
<INPUT TYPE=TEXT NAME="ssn_3" MAXLENGTH=4 SIZE=4><BR>
email: <INPUT TYPE=TEXT NAME="email"><BR>
To set the three fields as automatics jumpers, we add a short script immediately after
closing the form. The script must come immediately after the form before any other
forms. We use the autojump() command once for each field which must auto-jump.
autojump() takes three argument: the name of the field which should auto-jump, the name
of the field to jump to, and how many characters fills up the field. So these commands set
ssn_1 to jump to ssn_2 after three characters, ssn_2 to jump to ssn_3 after two characters,
and ssn_3 to jump to email after four characters.
autojump('ssn_1', 'ssn_2', 3);
autojump('ssn_2', 'ssn_3', 2);
autojump('ssn_3', 'email', 4);