Copy Code code as follows:
function Banbackspace (e) {
var ev = e | | window.event;//Get Event Object
var obj = Ev.target | | ev.srcelement;//Get Event Source
var t = Obj.type | | Obj.getattribute (' type ');//Get Event Source Type
Get the event type as a criterion
var vreadonly = obj.readonly;
var vdisabled = obj.disabled;
Handling Undefined values
Vreadonly = (Vreadonly = = undefined)? False:vreadonly;
vdisabled = (vdisabled = = undefined)? true:vdisabled;
When you hit the BACKSPACE key, the event source type is a password or a single line, multi-line text,
And the ReadOnly property is true or the disabled property is true, the backspace key is invalidated
var Flag1 = Ev.keycode = 8 && (t = = "password" | | t = = "text" | | | = = "TEXTAREA") && (vreadonly = = True | | vdisabled = = true);
When the BACKSPACE key is hit, the event source type is not a password or a single line or multi-line text, the BACKSPACE key is invalidated
var Flag2 = Ev.keycode = = 8 && t!= "password" && t!= "text" && t!= "textarea";
Judge
if (Flag2 | | flag1) return FALSE
}
Disable backspace key for Firefox, Opera
document.onkeypress = Banbackspace;
Disable backspace key for IE, Chrome
Document.onkeydown = Banbackspace;
