Javascript HTML背景图像被放大

我试图每5秒更改一个部分的背景图像，我已经通过使用JavaScript成功地做到了这一点。但问题是图像被放大了。我做错了什么

HTML:

---

可能图像大小不合适，请尝试将

背景大小设置为
封面
：

HTML:

如果要查看完整图像大小，请执行以下操作：

first[0] = "url('1.jpg') no-repeat;background-size: contain;";
first[1] = "url('2.jpg') no-repeat;background-size: contain;";
first[2] = "url('3.jpg') no-repeat;background-size: contain;";

first[0] = "url('1.jpg') no-repeat center center;background-size: cover;";
first[1] = "url('2.jpg') no-repeat center center;background-size: cover;";
first[2] = "url('3.jpg') no-repeat center center;background-size: cover;";


您还可以通过百分比/像素/设置图像大小。。。相似背景大小：50%；
**如果使用contain，并且图像大小过大，则可能导致溢出

如果要查看与元素大小相关的图像，请执行以下操作：

first[0] = "url('1.jpg') no-repeat;background-size: contain;";
first[1] = "url('2.jpg') no-repeat;background-size: contain;";
first[2] = "url('3.jpg') no-repeat;background-size: contain;";

first[0] = "url('1.jpg') no-repeat center center;background-size: cover;";
first[1] = "url('2.jpg') no-repeat center center;background-size: cover;";
first[2] = "url('3.jpg') no-repeat center center;background-size: cover;";


（背景大小：封面）将剪切图像（如果需要）并设置为元素大小。
**如果你想使用这种风格，最好是图像大小相同，这可能是你的最佳选择

祝你好运
旁注；您的
x
修改逻辑可以减少为
x=++x%图像。如果您像使用css中的背景图像写入
背景大小：封面那样使用，则长度
图像看起来更小，并且大小调整为容器的高度和宽度。
first[0] = "url('1.jpg') no-repeat;background-size: contain;";
first[1] = "url('2.jpg') no-repeat;background-size: contain;";
first[2] = "url('3.jpg') no-repeat;background-size: contain;";

first[0] = "url('1.jpg') no-repeat center center;background-size: cover;";
first[1] = "url('2.jpg') no-repeat center center;background-size: cover;";
first[2] = "url('3.jpg') no-repeat center center;background-size: cover;";