PDFKit，无法打开生成的pdf

我正在尝试使用我自己的一些文本(而不是 html 页面)生成 pdf.我尝试使用 PDFKit.我能够生成 pdf，但随后我无法在 Preview 中打开它(它可能已损坏或使用了 Preview 无法识别的文件格式.)

I am trying to generate a pdf using some texts of my own (and not a html page). I tried using PDFKit. I am able to generate the pdf but then I am not able to open it in Preview (It may be damaged or use a file format that Preview doesn’t recognize.)

下面是代码，

var fs = require('fs');
PDFDocument = require ('pdfkit');
var doc = new PDFDocument

// Embed a font, set the font size, and render some text
doc.text('Some text with an embedded font!', 100, 100)

// Add another page
doc.addPage()
   .text('Here is some vector graphics...', 100, 100)

// Draw a triangle
doc.save()
   .moveTo(100, 150)
   .lineTo(100, 250)
   .lineTo(200, 250)
   .fill("#FF3300")

// Apply some transforms and render an SVG path with the 'even-odd' fill rule
doc.scale(0.6)
   .translate(470, -380)
   .path('M 250,75 L 323,301 131,161 369,161 177,301 z')
   .fill('red', 'even-odd')
   .restore()

// Add some text with annotations
doc.addPage()
   .fillColor("blue")
   .text('Here is a link!', 100, 100)
   //.underline(100, 100, 160, 27, color: "#0000FF")
   .link(100, 100, 160, 27, 'http://google.com/')

// Write the PDF file to disk
doc.pipe(fs.createWriteStream('out.pdf') );
doc.end

我可能遗漏了一些小东西.

I might be missing something small. P