按要求填空。 function fun1(a, b, callback){ if(typeof(a) == "number" && typeof(b) == "number"){ callback(a, b); }else{ console.log("Not a Number"); } } fun1(10, 20, function(x, y){ console.log(x > y? x : y); }); //输出为( 1 ) fun1("10", "20", function(x, y){ console.log(x + y); }); //输出为( 2 )