Waiting for promise in for loop

Question

I have a bit of trouble getting into this whole async stuff. I\'m using pdf.js to read the contents of a pdf file. Everything is working, however the execution order is caus

Answer 1

you can use async/await

async function getText(data) {
    var contents = [];
    var pdf = await PDFJS.getDocument(data);

    var numPages = pdf.pdfInfo.numPages;

    for (var i = 1; i <= numPages; i++) {
      var page = await pdf.getPage(i);
      var content = await page.getTextContent();

      contents.concat(content.bidiTexts);      
    }    
}

Note that getText will return a promise, you can use async /await again to access the result or getText(data).then(result => console.log(result));

if you want to get the pages in parallel, use Promise.All then await for the .getContent() :

async function getText(data) {
  var pdf = await PDFJS.getDocument(data)
  var numPages = pdf.pdfInfo.numPages;

  var promises = [];

  for (var i = 1; i <= numPages; i++) {
    promises.push(pdf.getPage(i));
  }

  var result = await Promise.All(promises)
    .then(pages => pages.map(page => await page.getTextContent()));

  return result;
}