How Can I Access the Value of a JavaScript Promise?

Accessing the Value of a Promise

In JavaScript, promises are used to represent asynchronous operations. They provide a way to chain together multiple asynchronous operations and access the result of each operation once it completes.

When you call .then() on a promise, you're creating a new promise that is resolved when the original promise is resolved. The value passed to .then()'s callback function is the result of the original promise.

In the example from Angular's documentation, promiseB is a new promise that is resolved immediately after promiseA is resolved. The value of promiseB is the result of promiseA incremented by 1.

To access the value of promiseB, you can call .then() on it and pass a callback function. The callback function will receive the value of promiseB as its argument.

promiseB.then(function(result) {
  // here you can use the result of promiseB
});

As of ES7 (2016), Promises have been enhanced with async/await syntax. Using async/await, you don't need to use .then() to access the value. Instead, you can use await to suspend the execution of your code until a promise is resolved.

let result = await functionThatReturnsPromiseA();
result = result + 1;

In this case, result will contain the result of promiseA incremented by 1. However, await can only be used within async functions.

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