__zone_symbol__value

The answer to your query, “__zone_symbol__value”, is explained below.

The “__zone_symbol__value” is a symbol used in Zone.js library, which is a transparent mechanism for automatically running tasks in a specific zone. It provides hooks to track the start and end of asynchronous tasks and enables developers to capture and handle various events in the application.

In the context of Zone.js, “__zone_symbol__value” is a special symbol that is used as a key in the task object to access the return value of an asynchronous task. It allows developers to access the resolved or rejected value of Promises, Observables, or other asynchronous operations wrapped in a zone.

Here is an example to demonstrate the usage of “__zone_symbol__value”:

// Create a promise within a zone
zone.run(() => {
  const promise = new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve('Promise resolved!');
    }, 1000);
  });
  
  // Access the resolved value using __zone_symbol__value
  promise.then((__zone_symbol__value) => {
    console.log(__zone_symbol__value); // Output: "Promise resolved!"
  });
});

In the above example, Zone.js is used to create a new zone, where a promise is created. The setTimeout function is wrapped within the zone, and when the promise resolves, the resolved value can be accessed using “__zone_symbol__value” within the “then” callback.