JavaScript, async and await keywords

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As you should already know, a promise can be rejected. So you should ask yourself: How do we deal with a rejected promise when using async and await ? If you remember the playground on promises, you learned this:

You can use the promise's catch like a normal catch. And everything is simple to understand. Keep in mind that a then callback can crash. It can throw an error (with an explicit throw or by trying to access a property of a null variable). The catch method will also catch these crashes. Repeat to yourself: the promise's catch method is like a normal catch.

So, what is the most natural way to handle an error when using async and await ? Yes, you have it. Use a simple try { ... } catch (error) { ... }. Look at the following example:

Error handling example

function job() {
    return new Promise(function(resolve, reject) {
        setTimeout(reject, 500, 'Error happened');
    });
}
async function test() {
    try {
        let message = await job();
        console.log(message);
        return 'Hello world';
    } catch (error) {
        console.error(error);
        return 'Error happened during test';
    }
}
test().then(function(message) {
    console.log(message);
});

If you want to return a rejected promise in an async function, you just have to throw an error. Look at this example:

Return a rejected promise

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