AJAX call in array loop, call next only after previous complete

问题

I have an array to upload data and I want them to send to server one by one. I want the previous one to complete before I send next one. Actually, after each response I want to decide whether to send next one or not.

while (packetCount < bulkUploadPackets.length) {
  d = d.then(save(bulkUploadPackets[packetCount]))
    .then(function(uploadResponse) {
      //I want to come here after first call complete 
      //before second call is fired and so on
      packetCount++;
    });
}


save: function(modelToSave) {
  var defer = $.Deferred();
  var self = this;
  this.model = modelToSave;
  Backbone.sync('create', this, {
    success: function(data, textStatus, jqXHR) {
      console.log("success" + data);
      defer.resolve(data);
    },
    error: function(response) {
      defer.reject(errorObj);
    }
  });

  return defer.promise();
}

回答1:

You can use recursive function and put recursive call inside then:

(function loop() {
     if (packetCount<bulkUploadPackets.length) {
           d = d.then(save(bulkUploadPackets[packetCount]))
                .then(function(uploadResponse){
                      //I want to come here after first call complete before second call is fired and so on
                      packetCount++;
                      loop();
                 }); 
     }
})();

来源：https://stackoverflow.com/questions/36626803/ajax-call-in-array-loop-call-next-only-after-previous-complete