Overridden shouldComponentUpdate() should not always return a truthy value
- REACT_USELESS_SHOULD_COMPONENT_UPDATE
- Code Quality
- Low
- react
This rule applies when an overridden shouldComponentUpdate() method always returns a truthy value.
Since shouldComponentUpdate() defaults to true, it is useless if the overridden shouldComponentUpdate() method always returns a truthy value.
In this case, shouldComponentUpdate() method's logic is probably wrong by a developer's mistake or misunderstanding of the method.
Noncompliant Code Example
View with compliant examples side by sideimport React from 'react';
export class Hello extends React.Component {
constructor(props) {
super(props);
this.state = { greetName: 'Hi' };
this.handleClick = this.handleClick.bind(this);
}
handleClick() {
this.setState({ greetName: 'Bye' });
}
shouldComponentUpdate(nextProps, nextState) { // REACT_USELESS_SHOULD_COMPONENT_UPDATE alarm because this always returns true.
if (nextState.greetName !== this.state.greetName) {
return true;
}
return true;
}
render() {
return <div onClick={this.handleClick}>{this.state.greetName}</div>;
}
}Compliant Code Example
View with noncompliant examples side by sideimport React from 'react';
export class Hello extends React.Component {
constructor(props) {
super(props);
this.state = { greetName: 'Hi' };
this.handleClick = this.handleClick.bind(this);
}
handleClick() {
this.setState({ greetName: 'Bye' });
}
shouldComponentUpdate(nextProps, nextState) {
if (nextState.greetName !== this.state.greetName) {
return true;
}
return false;
}
render() {
return <div onClick={this.handleClick}>{this.state.greetName}</div>;
}
}Version
This rule was introduced in DeepScan 1.4.0-beta.