go 服务端：

就是先把这个图片读出来  然后返回二进制的数据

byteFile, err := ioutil.ReadFile("."  + "/processed/" + uuidStr+"processed.png")if err != nil {fmt.Println(err)}c.Header("Content-Disposition", "attachment; filename=file-name.txt")c.Data(http.StatusOK, "application/octet-stream", byteFile)

js 前端获取图片：

function doSomething() {//	var videoData = "";var fileObj = document.getElementById("fileimage").files[0]; // js 获取文件对象var formData = new FormData();formData.append("file", fileObj); //上传一个files对象// formData.append("参数", "参数1"); //若需要上传的多个参数// formData.append("参数", "参数2");var url = "http://127.0.0.1:8000/upload/histogram";$.ajax({url: url,// dataType:"text",// dataType: "json",type: "post",data: formData,processData : false, //不处理发送的数据contentType: false, //不设置Content-Type请求头xhrFields:{responseType: 'blob'},success: function(res) {console.log(111)var img = document.getElementById('img-from-local-storage');var url = window.URL || window.webkitURL;img.src = url.createObjectURL(res);

    <img id="img-from-local-storage" />

参考文章：

Sending image files from back-end to front-end - JavaScript - The freeCodeCamp Forum