JavaScript 使用 FileReader 实现图片上传与预览

<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
		.file-ipt{position: absolute;left:0;top: 0;opacity: 0;width: 50px;height: 25px;}  //这里透明化了input框，然后绝对定位在按钮上了
		.btn{width: 50px;height: 25px; background-color: skyblue;color: white;margin-right: 80px;border: none;border-radius: 10px;font-size: 8px;}
		</style>
	</head>
	<body>
		<button class="btn">图片</button>
		<input type="file" id="file" accept="image/jpg,imgae/jpeg,image/png" class="file-ipt" onchange="insertimg(this);"><br>
		<img src="" id="img1" alt="">
		<script language="javascript">
			function insertimg(img){
				var rd=new FileReader();
				files=img.files[0];
				var filetype=files.type.slice(6,10);
				if(filetype!='jpg'&&filetype!='jpeg'&&filetype!='png'){
					alert('仅支持png,jpeg,jpg图片格式');
					return;
				}else{
					rd.readAsDataURL(files);
					rd.onloadend=function(e){
						document.getElementById('img1').src=e.target.result;
						document.getElementById('img1').style.width="300px";
						document.getElementById('img1').style.height="auto";
					};
				}
			}
		</script>
	</body>
</html>

HTML 与 JavaScript 代码实现

 <ul class="crgoods_uploadUl clearfix">
     <li><img src="img/product1.jpg"></li>
     <li><img src="img/product1.jpg"></li>
     <li class="add"><i>+</i>最多20张<input type="file" class="liAdd_flie" οnchange="liUploadImg(this)"></li>
</ul>

//商品相册图片上传预览
    function liUploadImg(file){     
        if (file.files && file.files[0]){
            var reader = new FileReader();
            reader.onload = function(evt){ 
                // imgUpload.src = evt.target.result;
                $('.crgoods_uploadUl li.add').before('<li><img src="'+evt.target.result+'"></li>');   
            }
            reader.readAsDataURL(file.files[0]);
        }else{ 
            var sFilter='filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="';
            file.select();
            var src = document.selection.createRange().text;
            imgUpload.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = src;
        }
    }