throttleRequestByServer(url, requestFunction)Promise

Because browsers throttle the number of parallel requests allowed to each server, this function tracks the number of active requests in progress to each server, and returns undefined immediately if the request would exceed the maximum, allowing the caller to retry later, instead of queueing indefinitely under the browser's control.
Name Type Description
url String The URL to request.
requestFunction throttleRequestByServer~RequestFunction The actual function that makes the request.
Either undefined, meaning the request would exceed the maximum number of parallel requests, or a Promise for the requested data.
// throttle requests for an image
var url = '';
var requestFunction = function(url) {
  // in this simple example, loadImage could be used directly as requestFunction.
  return Cesium.loadImage(url);
var promise = Cesium.throttleRequestByServer(url, requestFunction);
if (!Cesium.defined(promise)) {
  // too many active requests in progress, try again later.
} else {
  promise.then(function(image) {
    // handle loaded image

Type Definitions


A function that will make a request if there are available slots to the server.
Name Type Description
url String The url to request.
A promise for the requested data.