嗨，有人可以帮忙解释一下为什么我的代码无法正常工作吗？

function Books(title, author, pages, info) {
  this.title = title
  this.author = author
  this.pages = pages
  this.info = function() {
    return this.title + 'by' + this.author + ',' + this.pages + 'pages' + ',' + 'have read!'
  }
}

var books = new Books('Behold a Pale Horse', 'Bill Cooper', 505)

books.info()