Hello 👋 Hope all are doing good in this pandemic time.
Whenever i am seeing any reactjs code snippets in internet i am noticing the unnecessary usage of
In react updating a state is a very expensive in terms of performance. The main reason is whenever the state updates the component will re-render again.
Here is an small example:
In the above code i created a counter using
useState when i am incrementing the counter
App component is re-rendering again. There if you check the logs
Component initialised got printed 4 times (1st time when component initialised and 3 times when i clicked on the
+ button). It is re-rendering the
App component because i am updating the state on click of the
Here we need to use state because our intention is to show the
counter value in the document.
Consider the following code 👇🏻
Here i am using two state variables one is for value next is to set type of input. Do we really need two state variables 🤔 ?. Actually why don't we try building this component without state ? the reason why i am saying like this is assume if we are building a form has many input fields in that case we need to pass value state to
input component from
form component if that's the case entire form component will re-render on every keystroke in any input.
In the second example actually we don't need state.
useRef is fine. Check the below code 👇🏻
in the ☝🏻 snippet we are not using state but still we able to achieve what we want without out re-rendering. Even in form use case instead if passing state from
input we can pass ref it will prevent unnecessary re-renders.
So what i would suggest is whenever you are dealing DOM manipulation like changing class name conditionally or changing any attribute of element etc.. then try to use
useRef instead of
useState. it will prevent your app from too many re-renders.
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