html如何导出为pdf格式？如何在一个js文件中，将一个函数注册到vue.prototype上？

// 导出页面为PDF格式
import html2Canvas from 'html2canvas'
import JsPDF from 'jspdf'
export default {
    install(Vue, options) {
        Vue.prototype.getPdf = function() {
            var title = this.htmlTitle
            html2Canvas(document.querySelector('#pdfDom'), {
                allowTaint: true
            }).then(function(canvas) {
                let contentWidth = canvas.width
                let contentHeight = canvas.height
                    // let contentHeight = canvas.height
                let pageHeight = contentWidth / 592.28 * 841.89
 
                console.log(pageHeight)
                    // let pageHeight = 10000000
                let leftHeight = contentHeight
                let position = 0
                let imgWidth = 595.28
                let imgHeight = 592.28 / contentWidth * contentHeight
                let pageData = canvas.toDataURL('