The document discusses various methods to force a React component to re-render without explicitly calling setState, emphasizing that components typically re-render when their state or props change. While force updates can be performed in class components, they are discouraged as they deviate from React's principles, and alternatives such as changing the key prop or using the useState hook should be considered. Ultimately, it is recommended to rely on props and state for re-renders to maintain component purity and efficiency.

2. How can you force react components to rerender
without calling the set state?
• React components re-render on their own whenever there are some
changes in their props or state. Simply updating the state, from a
random place in the code, causes the User Interface (UI) elements
that get re-rendered automatically.
• In class components, you have the option to call force update to force
a rerender. In function components, however, there’s no chance of
force update as there is no equivalent, but you have the option to
contrive a way to force updates with the help of the useState hook.
Force update must be tried and avoided as it deviates from a React
mindset. The React docs cite some examples of when force updates
can be used.

3. • By default, when there is a change in a component’s state or props,
the component will re-render. However, if there are implicit changes
like changes in deep data within an object that too without the object
itself changing or if your method to render depends on another data,
you have the option to tell React that it requires to re-run render just
by calling force update.

4. Force Update:
• However, an idea has been proposed that with deeply nested objects,
what becomes necessary is the force update. With taking help of an
immutable data source, it becomes cheap to track changes. The
change will always lead to a new object. Thus, we are only required to
check and see if the object reference has changed or not. You can
even use the library Immutable JS to implement immutable data
objects into the app.

5. • Generally, you must try to avoid the use of force updates and should
only read from this. props as well as this. state that is there in the
render. This makes the react component “pure” and the application
much easier and at the same time quite efficient. Changing the
element key that you want to re-render will work. You must set the
key prop on the element via state and then set the state to have a
new key when you want to update.
• By doing this, a change occurs and then you are required to reset the
key to this. setState ({key: Math. random}); You must note that this
will help you replace the element that is changing the key. An
example of how it could be useful is when there is a file input field
that you want to reset after uploading an image.

6. Review your Code:
• Also, you must note that if you are using force updates, you may want
to review your code and check if there is any other way to do the
same thing. Changing the key) will replace the element completely. If
you update the key to bring the required changes, you will probably
face an issue somewhere or the other in your code. Thus, using Math.
random the n key can help you re-create the element with every
render. It is not recommended to update the key in this manner
because react uses the key to effectively determine the best possible
way to re-render things.
• React developers struggle with unnecessary re-render components in
their applications. We have all gone through this when one
component keeps updating its data in the background and thus the
overall performance changes.

7. A quick note on Render:
• React’s createElement function help in creating and returning a new
element as per the given element type. All the updates are
automatically done whenever it’s required. Let us now see how the
re-render works in the class as well as the functional components.
• Here are a few methods to re-render a React component.

8. Re-render component when there is a change
in state:
• Whenever a React component state changes, React must run the
render method.
import React from 'react'
export default class App extends React.Component {
componentDidMount() {
this.setState({});
}
render() {
console.log('render() method')
return <p>Hi!<p>;
}
}

9. • In the example mentioned above, the state when the component
mounts are updated.
You even have the option to re-render an event component, for
example, a click event.
import React from "react";
export default class App extends React.Component {
state = {
mssg: ""
};
handleClick = () => {
this.setState({ mssg: "Hi there!" });
};
render() {
console.log("render() method");
return (
<>
{this.state.mssg}
</> ); } }

10. Output:
<button>Say something</button>
• Both the outputs will look somewhat like this:
render() method
render() method

11. Re-render component when props change:
import React from 'react'
class Child extends React.Component {
render() {
console.log('Child component: render()');
return
}
}

12. • In the example above, <Child/> component does not have a state.
However, it has a custom prop that is the message that it accepts.
• When the button is clicked on, it will update the <child/> component,
and the render lifecycle will be made to run again.
Child component: render()
Child component: render()

13. Re-render with a key prop:
• You can change the value of the key prop, and it will make React
unmount and re-mount the component again, and go through the
render lifecycle.
Force a re-render:
This method is highly discouraged and not a recommended one.
You should always use props & state to make a new render.
Nevertheless, this is how you may do it.

14. import React from 'react'
export default class App extends React. Component {
handleClick = () => {
// force a re-render
this.forceUpdate();
};
render() {
console.log('App component: render()')
return (
<>
</>
);
}
}

15. Output:
<button>Say something</button>

16. Conclusion:
• You must try to make your re-render count using the above-
mentioned resources that include in its talk the different examples
and case scenarios. If you are required to re-render a React
component, you should update the components state and props
Always.
• Try avoiding and causing re-render with a key prop as it will make it
more complex. Although there are some odd use cases where it is
required. However, you must keep in mind to never use force updates
to cause a re-render.
• Have any queries? or need any services in ReactJS? hire react js
developers from Bosc Tech. Get a free consultation from our experts
today!

17. • Content Source: https://bosctechlabs.com/force-react-components-
to-rerender-without-calling-set-state/

18. Thank You For Reading.
Keep In Touch.