Callbacks

Read first Task 31

A callback is a function passed to run later.

Definition and example

Callbacks is the focus of this lesson. A callback is a function passed to run later. The task asks you to apply that idea in a small example: What is a callback. Before you run the code, predict what should happen. Then Inspect the browser output and the value your code produces and compare it with your prediction. If the result differs, change one relevant line and run it again. Testing one change at a time makes the cause of a result easier to understand.

JavaScript 1 automatic check Async and APIs

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// TASK callbacks-01: What is a callback?
// STEPS: Read the explanation. Change one relevant line at a time, then run the code and compare the result with the check on the right.
setTimeout(()=>console.log('later'),0);
console.log('TODO');

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Your result

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Checks on this task:

The output must include “now”.

The task and step-by-step instructions are written as comments at the top of the editor. Change one relevant line, run it, and compare the result with these checks.

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Callbacks

Callbacks

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