jQuery.ajax file upload progress bar

XMLHttpRequest.upload monitors the progress when uploading files to the background. It mainly uses the XMLHttpRequestprovided uploadmethod, which returns an XMLHttpRequestUploadobject to represent the upload progress. - XMLHttpRequest.upload

FormData is XMLHttpRequesta new interface provided, the main advantage is that binary files can be uploaded asynchronously. - FormData

The specific operations are as follows

Page structure and style

<input type="file" id="upload-file">
<div class="progress">
    <div></div>
</div>
<button onclick="">上传</button>

.progress {
   width: 600px;
    height: 10px;
    border: 1px solid #ccc;
    border-radius: 10px;
    margin: 10px 0px;
    overflow: hidden;
}
/* 初始状态设置进度条宽度为0px */
.progress > div {
    width: 0px;     
    height: 100%;
    background-color: yellowgreen;
    transition: all .3s ease;
}

Function realization

function uploadFile() {
    //获取上传的文件
    var uploadFile = $('#upload-file').get(0).file[0];

    var formdata = new FormData();

    formdata.append('fileInfo', uploadFile);
    $.ajax({
        url: '/uploadfileurl',
        type: 'post',
        dataType: 'json',
        processData: false,
        contentType: false,
        xhr: function() {
            var xhr = new XMLHttpRequest();
            //使用XMLHttpRequest.upload监听上传过程，注册progress事件，打印回调函数中的event事件
            xhr.upload.addEventListener('progress', function (e) {
                console.log(e);
                //loaded代表上传了多少
                //total代表总数为多少
                var progressRate = (e.loaded / e.total) * 100 + '%';

                //通过设置进度条的宽度达到效果
                $('.progress > div').css('width', progressRate);
            })

            return xhr;
        }
    })
}

final effect