<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<input type="file" id="photo" accept="image/*">
<div id="click" style="width: 200px; height: 200px; border: 1px solid #000;"></div>
<script>
document.getElementById('photo').addEventListener('change',function(e){

var files = this.files;
var img = new Image();
var reader = new FileReader();
reader.readAsDataURL(files[0]);
reader.onload = function(e){
var mb = (e.total/1024)/1024;
if(mb>= 2){
alert('文件大小大于2M');
return;
}
img.src = this.result;
img.style.width = "100%";
img.style.height = "100%";
document.getElementById('click').innerHTML = '';
document.getElementById('click').appendChild(img);
}
});
</script>
</body>
</html>

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