下面哪一個 JavaScript 程式碼片段(code segment)，能正確定義與呼叫一個函數？
Afunction sum(x,y) {return x+y} var total = sum(); alert(total);
Bfunction sum(x,y) {return} var total = sum(20,6); alert(total);
Cfunction sum(x,y) {return} var total = sum(); alert(total);
Dfunction sum(x,y) {return x+y} var total = sum(20,6); alert(total);正確答案
答案與詳解
