var fileInput = document.getElementById("image")
fileInput.onchange = function(event){
if (this.files.length == 0) { return }
var oFile = this.files[0]
if (!/image.*/.test(oFile.type)) {return}
var img = document.createElement("img")
document.getElementById("display").appendChild(img)
var reader = new FileReader();
reader.onload = function(evt) {
img.src= evt.target.result;
}
reader.readAsDataURL(oFile)
// 或者用createObjectURL
img.src = window.URL.createObjectURL(file)
}

//下面用于图片上传预览功能
var imgInput = document.getElementById("imgInput")
var imgPreview = document.getElementById("preview")
imgInput.onchange = function(event){
if (imgInput.files && imgInput.files[0]) {
var file = imgInput.files[0]
// createObjectURL 方法同步，内存占用少，网页关闭或使用revokeObjectURL时释放
imgPreview.src = window.URL.createObjectURL(file)
// readAsDataURL 方法异步，内存占用多，垃圾回收
// var read = new FileReader();
// read.onload = function(event) {
//  imgPreview.src = event.target.result
// }
// read.readAsDataURL(file)
} else {
// IE10以下兼容
var imgSrc = imgInput.value
var localImag = document.getElementById("localImag");
try {
localImag.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
localImag.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgSrc;
} catch(e) {
alert("您上传的图片格式不正确，请重新选择!");
return false;
}
imgPreview.style.display = 'none';
}
}