Avoid Form Auto-advancing
Ensure that focus is never automatically advanced from form field to form field. This is often experienced when three text fields are used for telephone numbers (area code, first three digits, last four digits). After entering the first thee numbers, focus is automatically set via JavaScript to the second field, but a user who has pressed the tab key will then be moved to the third field. The problem can sometimes be compounded when the user attempts to fix an error. For example, if the first field contains an incorrect area code and the user presses Shift + Tab to go back to the field, the JavaScript may detect that the field already has three characters and automatically set focus to the next field, making it impossible to correct the field with the error. This can be avoided by not setting focus and simply allowing the user to move to the desired fields manually.
