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JavaScript Asynchronous Programming with JavaScript Understanding Promises Using Fetch

Samuel Kleos
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Samuel Kleos
Front End Web Development Techdegree Student 12,719 Points
Posted by Samuel Kleos
.a{fill-rule:evenodd;}techdegree
Samuel Kleos
Front End Web Development Techdegree Student 12,719 Points

When is the promise being created by fetch()?

Looking at the following line by line: 

btn.addEventListener('click', (event) => {
    event.target.textContent = "Loading...";
    fetch(astrosUrl)
        .then(response => response.json())
                .then(getProfiles)
        .then(generateHTML)
        .finally(() => event.target.remove());
});

Is the promise object being created after you pass astrosUrl to fetch() or is it being created by the .json() method.

1 Answer

Steven Parker
Steven Parker
229,788 Points
Steven Parker
Steven Parker
229,788 Points

The promise object is created immediately upon calling fetch, but at that time it will still be in a pending state. The .json() method is not called until later when the promise has been (successfully) resolved.