Can you force a React component to rerender without calling setState?

In 2021 and 2022, this is the official way to forceUpdate a React Functional Component.

const [, forceUpdate] = useReducer(x => x + 1, 0);

  function handleClick() {
    forceUpdate();
  }

I know the OP is for a class component. But the question was asked in 2015 and now that hooks are available, many may search for forceUpdate in functional components. This little bit is for them.

Edit 18th Apr 2022

It's usually bad practice to force update your components.

A few reasons that can cause the need to use force updates.

  • Not using state variables where you have to - local, redux, context.
  • The field from the state object you are trying to access and expecting to update/change is too deeply nested in objects or arrays. Even Redux advises to maintain flat objects or arrays. If only one field value changes in a complex object, React may not figure out that the state object has changed, thus it does not update the component. Keep your state flat and simple.
  • The key on your list items, as mentioned in another answer. In fact, this can cause other unexpected behaviors as well. I've seen lists where items are repeatedly rendered (duplicates) because the keys aren't identical or the keys are just missing altogether. Always request the backend team to send unique ids everywhere possible! Avoid using array indexes for keys. Do not try to create unique ids on the front-end by using nanoid, uuid or random. Because ids created using above methods change each time the component updates (keys provided to a list need to be static and the same on each render). Creating unique ids is usually a backend concern. Try your best to not bring that requirement to the front-end. The front-end's responsibility is only to paint what data the backend returns and not create data on the fly.
  • If your useEffect, useCallback dependency arrays do not have the proper values set. Use ESLint to help you with this one! Also, this is one of the biggest causes for memory leaks in React. Clean up your state and event listeners in the return callback to avoid memory leaks. Because such memory leaks are awfully difficult to debug.
  • Always keep an eye on the console. It's your best friend at work. Solving warning and errors that show up in the console can fix a whole lot of nasty things - bugs and issues that you aren't even aware off.

A few things I can remember that I did wrong. In case it helps..


In class components, you can call this.forceUpdate() to force a rerender.

Documentation: https://facebook.github.io/react/docs/component-api.html

In function components, there's no equivalent of forceUpdate, but you can contrive a way to force updates with the useState hook.


forceUpdate should be avoided because it deviates from a React mindset. The React docs cite an example of when forceUpdate might be used:

By default, when your component's state or props change, your component will re-render. However, if these change implicitly (eg: data deep within an object changes without changing the object itself) or if your render() method depends on some other data, you can tell React that it needs to re-run render() by calling forceUpdate().

However, I'd like to propose the idea that even with deeply nested objects, forceUpdate is unnecessary. By using an immutable data source tracking changes becomes cheap; a change will always result in a new object so we only need to check if the reference to the object has changed. You can use the library Immutable JS to implement immutable data objects into your app.

Normally you should try to avoid all uses of forceUpdate() and only read from this.props and this.state in render(). This makes your component "pure" and your application much simpler and more efficient.forceUpdate()

Changing the key of the element you want re-rendered will work. Set the key prop on your element via state and then when you want to update set state to have a new key. 

<Element key={this.state.key} />

Then a change occurs and you reset the key

this.setState({ key: Math.random() });

I want to note that this will replace the element that the key is changing on. An example of where this could be useful is when you have a file input field that you would like to reset after an image upload.

While the true answer to the OP's question would be forceUpdate() I have found this solution helpful in different situations. I also want to note that if you find yourself using forceUpdate you may want to review your code and see if there is another way to do things.

NOTE 1-9-2019:

The above (changing the key) will completely replace the element. If you find yourself updating the key to make changes happen you probably have an issue somewhere else in your code. Using Math.random() in key will re-create the element with each render. I would NOT recommend updating the key like this as react uses the key to determine the best way to re-render things.

Tags:

Reactjs

React Jsx

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