JavaScript Error Handling Interaction with Promises
Example
6
Exceptions are to synchronous code what rejections are to promise-based asynchronous code. If an exception is thrown in a promise handler, its error will be automatically caught and used to reject the promise instead.
Promise.resolve(5)
.then(result => {
throw new Error("I don't like five");
})
.then(result => {
console.info("Promise resolved: " + result);
})
.catch(error => {
console.error("Promise rejected: " + error);
});
Promise rejected: Error: I don't like five
7
The async functions proposal—expected to be part of ECMAScript 2017—extends this in the opposite direction. If you await a rejected promise, its error is raised as an exception:
async function main() {
try {
await Promise.reject(new Error("Invalid something"));
} catch (error) {
console.log("Caught error: " + error);
}
}
main();
Caught error: Invalid something
