这个pdf.js应该怎么用，报错 PDFJS is not defined

Question

这是从网上找到的一个例子，但是运行时报错了

 <script src="http://mozilla.github.io/pdf.js/build/pdf.js"></script>

    <h1>PDF.js Previous/Next example</h1>

    <canvas id="the-canvas"></canvas>

<script>
        var url = './123.pdf';
        PDFJS.workerSrc = 'http://mozilla.github.io/pdf.js/build/pdf.worker.js';

        var pdfDoc = null,
            pageNum = 1,
            pageRendering = false,
            pageNumPending = null,
            scale = 0.8,
            canvas = document.getElementById('the-canvas'),
            ctx = canvas.getContext('2d');

        function renderPage(num) {
            pageRendering = true;
            pdfDoc.getPage(num).then(function (page) {
                var viewport = page.getViewport(scale);
                canvas.height = viewport.height;
                canvas.width = viewport.width;

                var renderContext = {
                    canvasContext: ctx,
                    viewport: viewport
                };
                var renderTask = page.render(renderContext);

                renderTask.promise.then(function () {
                    pageRendering = false;
                    if (pageNumPending !== null) {
                        // New page rendering is pending 
                        renderPage(pageNumPending);
                        pageNumPending = null;
                    }
                });
            });

            document.getElementById('page_num').textContent = pageNum;
        }

        function queueRenderPage(num) {
            if (pageRendering) {
                pageNumPending = num;
            } else {
                renderPage(num);
            }
        }

        function onPrevPage() {
            if (pageNum <= 1) {
                return;
            }
            pageNum--;
            queueRenderPage(pageNum);
        }
        document.getElementById('prev').addEventListener('click', onPrevPage);

        function onNextPage() {
            if (pageNum >= pdfDoc.numPages) {
                return;
            }
            pageNum++;
            queueRenderPage(pageNum);
        }
        document.getElementById('next').addEventListener('click', onNextPage);

        PDFJS.getDocument(url).then(function (pdfDoc_) {
            pdfDoc = pdfDoc_;
            document.getElementById('page_count').textContent = pdfDoc.numPages;

            renderPage(pageNum);
        });
    </script>

这个是为什么

Answer 1

你加载的pdfjs库中没有PDFJS 这个变量或者对象
如下图

只有一个pdfjsLib对象
你试试使用pdfjsLib对象操作pdf
有帮助请点一下右上角的采纳,谢谢