JavaScript callback function | Simple example code

A JavaScript callback function is a function passed into another function as a parameter.

Using a callback, you could call another function with a callback, and let the first function run the callback after all statements completed.

JavaScript callback function Example

In the HTML example, addNum function accept 3 parameter. Where is 3rd parameter is callback function – displayResult.

So what is happening:-

First addNum will finish the addition of 2 number, then it will call the displayResult function to show the result.

Output:

JavaScript callback function example code

Q: When to Use a JavaScript Callback function?

Answer: The benefit of using a JS callback function is that you can wait for the result of a previous function call and then execute another function call.

Do comment if you have any doubts and suggestion on this JS function topic.

Note: All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version


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