Varcheckequal =false;//avoid Repetition CALCU
Varopflag =false;//check Repetition Add operation
Varuptext = document.getElementById ("Uptext");
varcal = document.getElementById ("cal"). Style;
Vardowntext = document.getElementById ("Downtext");
Functionclearalltext () {
Downtext.value =-downtext.value;
Functiondeleteonedigit () {
Downtext.value = downText.value.substring (0, downtext.value.length-1);
if (Downtext.value = = "" | | (downText.value.charAt (0) = = "-" && downText.value.charAt (1) = "") {
Functioncheckifaddpoint (num) {
if (num== "." && Downtext.value = = "0") | | Opflag ==true) {
}elseif (num = = "." && downText.value.indexOf (".") >-1) {
Functioncheckifaddnum (num) {
if ((Num!= ".") && Downtext.value = = "0" && downtext.value[1]!= ".")
|| Downtext.value = "Infinity"
Functionclickoperation (OP) {
Downtext.value = Checkdowntextvalid (Downtext.value);
Downtext.value = Checkzero (Uptext.value,downtext.value);
Uptext.value = Appenduptextvalue (uptext.value,downtext.value, "+");
Uptext.value = Appenduptextvalue (Uptext.value,downtext.value, "-");
Uptext.value = Appenduptextvalue (Uptext.value,downtext.value, "*");
Uptext.value = Appenduptextvalue (Uptext.value,downtext.value, "/");
Functioncheckdowntextvalid (Downtext) {
if (Downtext.charat (downtext.length-1) = = ".") {
Returndowntext.substring (0,downtext.length-1);
Functioncheckzero (Uptext,downtext) {
if (Uptext.charat (uptext.length-1) = = "/" && Downtext = = "0") {
Functionappenduptextvalue (oldvalue,newvalue,operation) {
Returnoldvalue = newvalue+operation;
Returnoldvaluee = oldvalue+newvalue+operation;
Returnoldvalue.substring (0, oldvalue.length-1) +operation;
Downtext.value = eval (uptext.value+downtext.value);
Window.document.onkeydown = Choosekey;
Functionchoosekey (evt) {
if (Evt.keycode =) {alert ("=");}
ElseIf (Evt.keycode = = 8) {deleteonedigit ();}
ElseIf (Evt.keycode = =) {Clearalltext ();}
ElseIf (Evt.keycode = =) {Clicknum (' 0 ');}
ElseIf (Evt.keycode = =) {clicknum (' 1 ');}
ElseIf (Evt.keycode = =) {Clicknum (' 2 ');}
ElseIf (Evt.keycode = = Wuyi) {clicknum (' 3 ');}
ElseIf (Evt.keycode = =) {clicknum (' 4 ');}
ElseIf (Evt.keycode = =) {Clicknum (' 5 ');}
ElseIf (Evt.keycode = =) {clicknum (' 6 ');}
ElseIf (Evt.keycode = =) {clicknum (' 7 ');}
ElseIf (Evt.keycode = =) {Clicknum (' 8 ');}
ElseIf (Evt.keycode = =) {clicknum (' 9 ');}
ElseIf (Evt.keycode = =) {Clicknum (' 0 ');}
ElseIf (Evt.keycode = =) {clicknum (' 1 ');}
ElseIf (Evt.keycode = =) {Clicknum (' 2 ');}
ElseIf (Evt.keycode = =) {clicknum (' 3 ');}
ElseIf (Evt.keycode = =) {clicknum (' 4 ');}
ElseIf (Evt.keycode = =) {Clicknum (' 5 ');}
ElseIf (Evt.keycode = = 102) {clicknum (' 6 ');}
ElseIf (Evt.keycode = =) {clicknum (' 7 ');}
ElseIf (Evt.keycode = =) {Clicknum (' 8 ');}
ElseIf (Evt.keycode = =) {clicknum (' 9 ');}
ElseIf (Evt.keycode = =) {clicknum ('. ');}
ElseIf (Evt.keycode = =) {clickoperation (' x ');}
ElseIf (Evt.keycode = =) {clickoperation (' + ');}
ElseIf (Evt.keycode = =) {clickoperation (' a ');}
ElseIf (Evt.keycode = = 109) {clickoperation ('-');}