How to debounce in Javascript?

Debounce is a technique that ensures that a function in your web application is not called too frequently which in turn optimises the performance of your application.

Example: There is a search box that invokes a function and makes a call to the server on every keystroke

You can see in the above image that API request happens for every letter even though we are interested in the result of the last request.

Following in the current implementation of our search box handler:

So we have an opportunity to reduce the number of calls here. To do that we will be writing a debounce function.

A debounce function is function that takes input an original function that executes our logic and number of milli seconds say wait. Debounce function will ensure that our original function is not called until wait milli seconds have been passed since its last call.

Below is the simple implementation of a debounce function

So our implementation of handleSearch becomes

Results?

You can see in the above image that with debounce API request is only made once.

You don’t always have to write a a debouce implementation. If your code base uses libraries like lodash, underscore.js, they provide debounce function with additional options.

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