Rules
no-unsafe-component-will-mount

no-unsafe-component-will-mount

Rule category

Suspicious.

What it does

Warns usage of UNSAFE_componentWillMount in class components.

Why is this bad?

Using unsafe lifecycle methods like UNSAFE_componentWillMount makes your component’s behavior less predictable and are more likely to cause bugs.

Examples

Failing

import React from "react";
 
class class ExampleExample extends React.class React.Component<P = {}, S = {}, SS = any>Component {
  // @warn: Do not use 'UNSAFE_componentWillMount'
  Example.UNSAFE_componentWillMount(): void
Called immediately before mounting occurs, and before {@link Component.render } . Avoid introducing any side-effects or subscriptions in this method. This method will not stop working in React 17. Note: the presence of {@link NewLifecycle.getSnapshotBeforeUpdate getSnapshotBeforeUpdate } or {@link StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps } prevents this from being invoked.
@deprecated16.3, use {@link ComponentLifecycle.componentDidMountcomponentDidMount} or the constructor instead@see{@link https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#initializing-state}@see{@link https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#gradual-migration-path}
UNSAFE_componentWillMount
() {
// ... } }