1. <select style=width:195px name=role id=role onfocus=this.defaultIndex=this.selectedIndex; onchange=this.selectedIndex=this.defaultIndex;>
This method can make the drop-down box not different from the usual ones and it doesn't look any different. The only difference is that after pulling down and selecting, it will not be the same as if it has not selected. It's just ignoring the customer's choice.
2. Set disabled attribute <select style=width:195px name=role id=role disabled=disabled>
This looks more direct and intuitive, just like reading only, and you can't click or pull down. The characters inside will also turn gray
When the property is set to disabled, the value of select cannot be passed when submitting the form. Remove the disabled property $(#role).removeAttr(disabled);
jquery adds attribute $(#role).attr(disabled,disabled);