jQuery异步上传文件上传图片

HTML:

<form enctype="multipart/form-data">
<input name="file" type="file" />
<input type="button" value="Upload" />
</form>
<progress></progress>

首先，你可以做一些验证，例如文件的onChange事件：

$(':file').change(function(){
    var file = this.files[0];
    name = file.name;
    size = file.size;
    type = file.type;
    //your validation
});

按钮点击触发Ajax:

$(':button').click(function(){
    var formData = new FormData($('form')[0]);
    $.ajax({
        url: 'upload.php',  //server script to process data
        type: 'POST',
        xhr: function() {  // custom xhr
            myXhr = $.ajaxSettings.xhr();
            if(myXhr.upload){ // check if upload property exists
                myXhr.upload.addEventListener('progress',progressHandlingFunction, false); // for handling the progress of the upload
            }
            return myXhr;
        },
        //Ajax事件
        beforeSend: beforeSendHandler,
        success: completeHandler,
        error: errorHandler,
        // Form数据
        data: formData,
        //Options to tell JQuery not to process data or worry about content-type
        cache: false,
        contentType: false,
        processData: false
    });
});

处理进度：

function progressHandlingFunction(e){
    if(e.lengthComputable){
        $('progress').attr({value:e.loaded,max:e.total});
    }
}

HTML5的文件上传非常简单，但必须在支持HTML5的浏览器中运行。