why react props are immutable

Why React Props are Immutable

React is a popular JavaScript library used for building user interfaces. It follows a unidirectional data flow, which means that data flows from parent components to child components via props. A prop is a short form for property, and it is a way for components to communicate with each other.

Props are immutable in React, which means they cannot be changed once they are set. This is because React uses a concept called "pure functions" to render UI components. A pure function is a function that always returns the same output for the same input, and it does not modify any data outside its scope.

When a component receives props from its parent component, it is expected to render itself based on those props. If the props were mutable, the component could alter them, which would make it difficult for React to track changes and efficiently update the UI. Immutable props ensure that components only render based on the data they received from their parents.

Immutable props also prevent components from accidentally modifying data that they should not have access to. If a component could modify its props, it could potentially alter data outside its scope, leading to unpredictable behavior in the application.

How to enforce immutability of props in React

There are several ways to enforce immutability of props in React. One common approach is to use the spread operator to create a new object that includes all the properties of the old object along with any additional properties that need to be added or updated.

const updatedProps = {...oldProps, newProp: 'new value'};

Another approach is to use object destructuring to extract only the properties that are needed into new variables. This ensures that the original object remains unchanged.

const {prop1, prop2} = props;

In summary, React props are immutable to ensure that components render based on the data they received from their parents and to prevent components from accidentally modifying data outside their scope. There are several ways to enforce immutability of props in React, including using the spread operator and object destructuring.