App使用pdf.js實現pdf預覽

第一步：下載pdf.js

下載地址：https://www.jsdelivr.com/package/npm/pdfjs-dist 

打開后找到pdf.js、pdf.work.js以及cmaps路徑下的全部文件，下載到本地或者直接引用其地址

實例代碼

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

//JS引用
<script type="text/javascript" src="../../script/pdf.js"></script>

//JS使用pdf.JS代碼
    var url = 'test.pdf'; 
    PDFJS.cMapUrl = 'https://cdn.jsdelivr.net/npm/pdfjs-dist@2.2.228/cmaps/';//字體解析
    PDFJS.cMapPacked = true;
    //加載核心文件 
    PDFJS.workerSrc = '../../script/pdf.worker.js';//或者https://cdn.jsdelivr.net/npm/pdfjs-dist@2.3.200/build/pdf.worker.js 
    var loadingTask = PDFJS.getDocument(url); 
    loadingTask.promise.then(function(pdf) { 
      console.log('PDF loaded'); 
      var pageNumber = 1; 
       pdf.getPage(pageNumber).then(function(page) { 
        console.log('Page loaded'); 
        var scale = 1; 
        var viewport = page.getViewport(scale); 
        var canvas = document.getElementById('the-canvas'); 
        var context = canvas.getContext('2d'); 
        canvas.height = viewport.height; 
        canvas.width = viewport.width; 
        var renderContext = { 
         canvasContext: context, 
          viewport: viewport 
         }; 
         var renderTask = page.render(renderContext); 
         renderTask.then(function () { 
          console.log('Page rendered'); 
         }); 
        }); 
       }, function (reason) { 
        console.error(reason); 
     });