问使用pdf.js时无法读取未定义的属性“”GlobalWorkerOptions“”

EN

<script src="//mozilla.github.io/pdf.js/build/pdf.js"></script>
<script>
    $(document).ready(function () {
            var pdfjsLib = window['pdfjs-dist/build/pdf'];

            // The workerSrc property shall be specified.
            pdfjsLib.GlobalWorkerOptions.workerSrc = '//mozilla.github.io/pdf.js/build/pdf.worker.js';
            let canvas = $('.pdfOferta');
            for (let i = 0; i < canvas.length; i++) {
                var pdfData = canvas[i].getAttribute['data-pdf'];
                var loadingTask = pdfjsLib.getDocument({ data: pdfData });
                loadingTask.promise.then(function (pdf) {
                    console.log('PDF loaded');
                    // Fetch the first page
                    var pageNumber = 1;
                    pdf.getPage(pageNumber).then(function (page) {
                        console.log('Page loaded');
                        var scale = 1.5;
                        var viewport = page.getViewport({ scale: scale });
                        // Prepare canvas using PDF page dimensions
                        var canvas = document.getElementById('the-canvas');
                        var context = canvas.getContext('2d');
                        canvas.height = viewport.height;
                        canvas.width = viewport.width;
                        // Render PDF page into canvas context
                        var renderContext = {
                            canvasContext: context,
                            viewport: viewport
                        };
                        var renderTask = page.render(renderContext);
                        renderTask.promise.then(function () {
                            console.log('Page rendered');
                        });
                    });
                }, function (reason) {
                    // PDF loading error
                    console.error(reason);
                });
            }
        });
</script>

<canvas class="pdfOferta" id="@Model.ListaDatasVivo[i].Ofertas[j].Arquivos[k].Id" data-pdf="@Model.ListaDatasVivo[i].Ofertas[j].Arquivos[k].ArqBase64"></canvas>

Cannot read property 'GlobalWorkerOptions' of undefined