JSPDF is undefined on IE 7

问题

I have page that need to be open in compatibility mode. I have add the JSPDF but it only works if I change to IE9 or above on IE7 it says JSPDF is undefined. any alternative to PDF a webpage on click of a button `

<script src="https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.3.2/jspdf.min.js"></script>

<script>
    function demoFromHTML() {

    alert("a");
      var doc = new jsPDF()

doc.text('Hello world!', 10, 10)
doc.save('a4.pdf') }
</script>
<a href="javascript:demoFromHTML()" class="button">PDF</a>

来源：https://stackoverflow.com/questions/53592650/jspdf-is-undefined-on-ie-7