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JavaScript随机背景图片大小

[英]Javascript random background image size

I have a code that shows a random background everytime I refresh, but I have no idea how I can make all images width100% and heigth 100%. 我有一个代码,每次刷新时都会显示随机背景,但是我不知道如何使所有图像的宽度分别为100%和高度100%。 Here's my code: 这是我的代码:

<html>
<head>
<script type="text/javascript"> 
var totalCount = 3;
function ChangeIt() 
{
var num = Math.ceil( Math.random() * totalCount );
document.body.background = 'bg'+num+'.png';
document.body.style.backgroundRepeat = "repeat";// bg repeat.
}
</script>
</head>
<body> 
----
</body> 
<script type="text/javascript"> 
ChangeIt();
</script> 
</html>

Any idea how to do this? 任何想法如何做到这一点?

You can try placing an image tag and setting the src property.That way , you can only specify the width and give an auto height. 您可以尝试放置图片标签并设置src属性,这样,您只能指定宽度并指定自动高度。

function ChangeIt() 
{
    var widthOfDoc = document.body.clientWidth;
    var num = Math.ceil( Math.random() * totalCount );
    var image = new Image();
    image.src = 'bg'+num+'.png';
    image.width = widthOfDoc;
    document.body.appendChild(image);
}

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