<!--
关键api：URL.createObjectURL(object) object:File对象或 Blob 对象
参考：https://developer.mozilla.org/zh-CN/docs/Web/API/URL/createObjectURL
-->
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<input type="file" id="ipt_file" onchange="selectChange()">
<script>
function selectChange(file){
var file = document.querySelector('#ipt_file').files[0];
var img = new Image();
img.onload = function(){
// 获取原宽高
alert(`width:${img.naturalWidth}, height:${img.naturalHeight}`);
}
img.src = URL.createObjectURL(file);
// 预览图片
document.body.appendChild(img);
}
</script>
</body>
</html>网络图片就直接把url赋给src就行
