求解代码运行的思路··

[a262740899]

var FlagNew=false;
var Opp="";
var total=0;
function entgernumber(Num){
if(FlagNew){
document.myform.txtNum.value=Num;
FlagNew=false;
}else {
if(document.myform.txtNum.value=="0"){
document.myform.txtNum.value=Num;
} else{
document.myform.txtNum.value+=Num;
}
}
}
function Operaton(Op){
var Num1=document.myform.txtNum.value;
if(FlagNew&& Opp != "=");{
FlagNew=true;
if('+'==Opp){
total+=parseFloat(Num1);
}else if('-'==Opp){
total-=parseFloat(Num1);
}else if('*'==Opp){
total*=parseFloat(Num1);
}else if('/'==Opp){
total/=parseFloat(Num1);
}else{
total=parseFloat(Num1);
}
document.myform.txtNum.value=total;
Opp=Op;

}
}

[浴火_凤凰]

加减运算？

[a262740899]

这是简易运算器代码··