if (typeof(123)="number") {} ,这个判断语法哪错了,为何过不去呢?

if (typeof(123)="number")  {} ,这个判断语法哪错了,为何过不去呢?
----------------------- if (typeof(123)="number")    // && typeof(vmonth)="number" && typeof(vdate)="number")
{
vdate=myform.txtdate.value;
mydate.setFullYear(vyear);
mydate.setMonth(vmonth);
mydate.setDate(vdate);
alert("当前日期为: " + mydate.toLocaleString());
alert(typeof(123));
}