我有这段代码：
/*
*
* Game Part 1: Getting the user's choice and the computer's randomly choice
*
*/
var userChoice = prompt("What's your nature element?");
var computerChoice = Math.random();
// get computer's randomly choice by "if" conditioning
if(computerChoice <= 0.25)
{
computerChoice = "water";
}
else if(computerChoice <= 0.50)
{
computerChoice = "fire";
}
else if(computerChoice <= 0.75)
{
computerChoice = "air";
}
else
{
computerChoice = "earth";
}
console.log("Computer's choosen element: " + computerChoice);
// This function will show the elements combination image
function show_combination_image(src) {
var img = document.createElement("img");
img.src = src;
// This line will just add it to the <body> tag
document.body.appendChild(img);
}
/*
*
* Game Part 2: Combining user's choice with computer's choice and returning the result
*
*/
var combine = function(element1, element2)
{
// if the choosen elements are the same
if(element1 === element2)
{
return "It seems that your element and computer's element are the same. You need to make a combination, therefore please insert a different element.";
}
// else if user chooses the "water" element
else if(element1 === "water")
{
if(element2 === "fire")
{
show_combination_image("img/water+fire.jpg");
}
else if(element2 === "air")
{
show_combination_image("img/water+air.jpg");
}
else (element2 === "earth")
{
show_combination_image("img/water+earth.jpg");
}
}
// else if user chooses the "fire" element
else if(element1 === "fire")
{
if(element2 === "water")
{
show_combination_image("img/water+fire.jpg");
}
else if(element2 === "air")
{
show_combination_image("img/fire+air.jpg");
}
else
{
show_combination_image("img/fire+earth.jpg");
}
}
// else if user chooses the "air" element
else if(element1 === "air")
{
if(element2 === "water")
{
show_combination_image("img/water+air.jpg");
}
else if(element2 ==="fire")
{
show_combination_image("img/fire+air.jpg");
}
else
{
show_combination_image("img/air+earth.jpg");
}
}
// else if user chooses the "earth" element
else if(element1 === "earth")
{
if(element2 === "water")
{
show_combination_image("img/water+earth.jpg");
}
else if(element2 === "fire")
{
show_combination_image("img/fire+earth.jpg");
}
else
{
show_combination_image("img/air+earth.jpg");
}
}
}
/*
*
* Game Part 3: Getting the user's element and the computer's randomly element and show the combination image
*
*/
combine(userChoice, computerChoice);<html>
<head>
</head>
<body>
</body>
</html>
我得到提示警告框，在我插入一些元素后，例如：水，火，土或空气，我只是得到空白页。 我希望显示由我选择的元素和计算机所选元素的组合产生的图像。
请告诉我代码有什么问题？