html 实现 上传图片到页面，直接展示，不需要上传到服务器目录（实现图片预览功能）
<html>
<head>
<meta charset="UTF-8">
<title></title>
<meta name="viewport" content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no" />
<style type="text/css">
#preview {
display: inline-block;
width: 2.56rem;
height: 2.56rem;
position: relative;
background-repeat: no-repeat;
background-size: cover;
}
#file {
width: 100%;
height: 100%;
opacity: 0;
position: absolute;
left: 0;
top: 0;
cursor: pointer;
z-index: 5;
}
</style>
</head>
<body>
<div id="preview" style="width:200px;heigth:200px;border:1px solid">
<input type="file" accept="image/*" id="file" value="" />
</div>
<script type="text/javascript">
var preview = document.querySelector('#preview');
var eleFile = document.querySelector('#file');
eleFile.addEventListener('change', function() {
var file = this.files[0];
// 确认选择的文件是图片
if(file.type.indexOf("image") == 0) {
var reader = new FileReader();
reader.readAsDataURL(file);
reader.onload = function(e) {
// 图片base64化
var newUrl = this.result;
preview.style.backgroundImage = 'url(' + newUrl + ')';
};
}
});
</script>
</body>
</html>
来源：CSDN
作者：紫薯馍馍
链接：https://blog.csdn.net/u012972294/article/details/103885196