如何为HTTP GET请求设置标头并触发文件下载？

尝试

html

<!-- placeholder ,     `click` download , `.remove()` options ,     at js callback , following js --><a>download</a>

js

        $(document).ready(function () { $.ajax({     // `url`      url: '/echo/json/',     type: "POST",     dataType: 'json',     // `file`, data-uri, base64     data: {         json: JSON.stringify({  "file": "data:text/plain;base64,YWJj"         })     },     // `custom header`     headers: {         "x-custom-header": 123     },     beforeSend: function (jqxhr) {         console.log(this.headers);         alert("custom headers" + JSON.stringify(this.headers));     },     success: function (data) {         // `file download`         $("a")  .attr({  "href": data.file,      "download": "file.txt"         })  .html($("a").attr("download"))  .get(0).click();         console.log(JSON.parse(JSON.stringify(data)));     },     error: function (jqxhr, textStatus, errorThrown) {       console.log(textStatus, errorThrown)     } });        });

jsfiddle
http://jsfiddle.net/guest271314/SJYy3/