Podcast
Questions and Answers
What is the expected output when the fetchData function is called?
What is the expected output when the fetchData function is called?
How long does the fetchData function wait before it resolves or rejects the promise?
How long does the fetchData function wait before it resolves or rejects the promise?
What role does the 'success' constant play in the fetchData function?
What role does the 'success' constant play in the fetchData function?
What will be logged to the console if fetchData is called correctly?
What will be logged to the console if fetchData is called correctly?
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Which line would cause the 'fetchData' function to execute successfully?
Which line would cause the 'fetchData' function to execute successfully?
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Study Notes
Function Overview
- The function
fetchDatais defined to return a promise. - Promises are used to handle asynchronous operations in JavaScript.
SetTimeout Mechanism
-
setTimeoutis utilized to simulate a delay of 2 seconds before executing the enclosed function. - This mimics fetching data from a network or any asynchronous operation.
Success Condition
- A variable
successis set to!true, which evaluates tofalse. - This indicates that the operation (data fetch) will not be successful in this scenario.
Promise Resolution
- If
successweretrue, the promise would resolve with an object containing a success message:{ data: "Get data successful!" }. - In the current state, when
successisfalse, the promise is rejected with an error message:"Failed to fetch data!".
Handling Promise Results
- The
fetchDatafunction is called, triggering the promise. - A
.then()method is used to handle the fulfilled and rejected states of the promise. - If the promise resolves, the success message would be logged to the console.
- Given the current condition, the error message will be logged to the console after 2 seconds.
Console Output
- Due to the rejection of the promise, the output after 2 seconds will be:
"Failed to fetch data!".
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Description
This quiz explores the concept of Promises in JavaScript, focusing on how they handle asynchronous operations. The provided function demonstrates a scenario where data fetching can either succeed or fail, showcasing the use of resolve and reject methods. Test your understanding of how Promises work in JavaScript.
