React warning React Hook useEffect has a missing dependency when the deps are []

Question

I am trying to clean up the warnings in my DOM, and for every useEffect where the deps are [] I get an error that says useEffect has a missing dependency. I want to trigger the effect when the component mounts, and I was under the impression that this was the way to do it. If thats the case, why the warning?

Here is the simple code im using

useEffect(() => {
   setDispContext("NEW");
}, []);

Warning is React warning React Hook useEffect has a missing dependency: 'setDispContext'. Either include it or remove the dependency array react-hooks/exhaustive-deps

Mvrocha · Accepted Answer · 2021-02-02 18:03:31Z

2

Everything that you use unside useEffect must be inside the dependency array, so the right way would be:

useEffect(() => {
   setDispContext("NEW");
}, [setDispContext]);

But sometimes you just need the useEffect to run once. If setDispContext won´t be change it can be put inside a useCallback. Otherwise the only waty would be to use :

useEffect(() => {
   setDispContext("NEW");
}, []);// eslint-disable-line

So the eslint warning won´t show.

edited Feb 2, 2021 at 18:03

answered Feb 2, 2021 at 17:57

Mvrocha

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bluebuddah · Accepted Answer · 2021-02-02 18:01:59Z

0

Try:

useEffect(() => {
   setDispContext("NEW");
// eslint-disable-line
}, []);

answered Feb 2, 2021 at 18:01

bluebuddah

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2 Comments

IWI Over a year ago

needed to go after the closing bracket

Melanie Shebel Over a year ago

While this code may provide a solution to the question, it's better to add context as to why/how it works. This can help future users learn and apply that knowledge to their own code. You are also likely to have positive-feedback/upvotes from users, when the code is explained.

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