var phantom = require('phantom');
var fs = require('fs');
var express = require('express');
var app = express();

app.get('/download', function(req, res) {
    //建立phantom例項
    phantom.create(function(ph) {
        //建立page例項
        ph.createPage(function(page) {
            //載入頁面
            page.open("template.html", function(status) {
                //設定剪輯的矩形
                page.evaluate(function() {
                        var selector = "#Viewport";
                        return document.querySelector(selector).getBoundingClientRect();
                    },
                    function(result) {
                        //設定剪輯框
                        page.set("clipRect", result);
                        //生成png圖片
                        page.render('a.png', {
                            format: 'png',
                            quality: '100'
                        }, function() {
                            //下載圖片到客戶端
                            res.download('a.png', "test.png");
                        });
                    });
            });
        });
    });
});
//設定http監聽
var server = app.listen(3040, function() {
    var host = server.address().address;
    var port = server.address().port;
    console.log('Example app listening at http://%s:%s', host, port);
});
 

res.download(<sourcefilepath>, <downloadfilename>);

參考