CODEWITHSUNDEEP
javascriptjqueryasynchronouspromise
ESP32
ESP32

Reputation: 8709

jQuery promise (variable number of promises)

I have a script that loads multiple SVG files and should then draw them. https://plnkr.co/edit/offqAzlaR1xqGrROQBTc

  var s = Snap("#svg");
  var bigCircle = s.circle(150, 150, 100);

  // Helper to convert Snap.load() into a Promise.
  function loadSVG(url) {
    var deferred = new $.Deferred();
    Snap.load(url, function(x) {
      deferred.resolve( x );
    });
    return deferred.promise();
  }

  // Make an array of Promises.
  var loadPromises = [
    loadSVG('eu.svg'),
    loadSVG('af.svg'),
    loadSVG('am.svg'),
    loadSVG('as.svg'),
  ];

  // Wait for all the Promises to finish.
  $.when( loadPromises ).done(function ( results ) {
    console.log(results); //<-- seems to be a promise again!!!!
    for (var i = 0; i < results.length; ++i) {
      var svg = results[i];
      // Your processing of each SVG goes here.
      var g = svg.select("g");
      s.append(g);
    }    
  });

I don't get any errors, but the strange thing is, that my done() result seems to be a promise again (at least it looks like that in the console). The result of done() should be an array of SnapJs objects. What am I doing wrong?

Upvotes: 2

Views: 525

Answers (1)

adeneo
adeneo

Reputation: 318182

You'll have to use apply to pass in an array of arguments to $.when

$.when.apply($, loadPromises).done(function () {
    var results = [].slice.call(arguments);

    ....
});

This then equals

$.when(loadPromises[0], loadPromises[1], loadPromises[2], etc)

Upvotes: 8

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