Using Angular $scope in web workers

Question

Using Angular $scope in web workers

What is the best way to access angular $scope data in Web Workers?

I'm currently experimenting with using parallel.js library for this purpose.

$scope.variant = 7;
$scope.final = 0;
var p = new Parallel([0, 1, 2, 3, 4, 5, 6]),
log = function () { console.log(arguments); };

function calculate(n) {
   $scope.final += n * $scope.variant;
};

p.map(calculate).then(log)

However, I encountered the following error:

 Uncaught ReferenceError: $scope is not defined

javascript angularjs web-worker

Answer 1

Answer №1

When utilizing Web Workers, a new thread is spawned resulting in a separate instance of the Angular app. This means that the code running in the worker is isolated from the main app unless you establish a method of communication such as sessionStorage, localStorage, cookies, or API calls. However, it is crucial to find a way to pass the necessary $scope into the worker.

In general, it is not recommended to have two threads manipulating the same $scope (even if it is achievable). Web Workers are typically employed for intensive tasks independent of the main app, with results passed back to the main app for further utilization (e.g., rendering complex images and returning them for display).

UPDATE

Here is a simplified example of how this can be achieved. The worker script does not use Angular but handles files independently:

Controller

var worker = new Worker('iterator.js');

worker.addEventListener('message', function(e) {
  console.log('Worker said: ', e.data);
  $scope.final = e.data; // for example
  $scope.$apply();       // perform a digest cycle
}, false);

Worker Script

function iterate() {
    // Perform iteration and data collection here
    // Send the collected data after processing:
    self.postMessage(collectedData);
}

You can also send parameters to the worker and call the iterate function with arguments.

The examples provided were derived from http://www.html5rocks.com/en/tutorials/workers/basics/ to serve as a guide on the implementation. Utilize workers for resource-intensive tasks and only transmit necessary data back to the main app.

Answer 2

When utilizing Web Workers, a new thread is spawned resulting in a separate instance of the Angular app. This means that the code running in the worker is isolated from the main app unless you establish a method of communication such as sessionStorage, localStorage, cookies, or API calls. However, it is crucial to find a way to pass the necessary $scope into the worker.

In general, it is not recommended to have two threads manipulating the same $scope (even if it is achievable). Web Workers are typically employed for intensive tasks independent of the main app, with results passed back to the main app for further utilization (e.g., rendering complex images and returning them for display).

UPDATE

Here is a simplified example of how this can be achieved. The worker script does not use Angular but handles files independently:

Controller

var worker = new Worker('iterator.js');

worker.addEventListener('message', function(e) {
  console.log('Worker said: ', e.data);
  $scope.final = e.data; // for example
  $scope.$apply();       // perform a digest cycle
}, false);

Worker Script

function iterate() {
    // Perform iteration and data collection here
    // Send the collected data after processing:
    self.postMessage(collectedData);
}

You can also send parameters to the worker and call the iterate function with arguments.

The examples provided were derived from http://www.html5rocks.com/en/tutorials/workers/basics/ to serve as a guide on the implementation. Utilize workers for resource-intensive tasks and only transmit necessary data back to the main app.

Using Angular $scope in web workers

Answer №1

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