November 2018
Beginner
502 pages
10h 22m
English
Content preview from Learn React with TypeScript 3
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shouldComponentUpdate
shouldComponentUpdate is invoked just before rendering happens. It returns a Boolean value that determines whether rendering should happen. It can be used to optimize performance, preventing unnecessary render cycles.
- Let's have a look at this life cycle method in our app by adding the following method:
public shouldComponentUpdate(nextProps: {}, nextState: IState) { console.log("shouldComponentUpdate", nextProps, nextState); return true;}
If we look at the running app, we see that shouldComponentUpdate happens between getDerivedStateFromProps and getSnapshotBeforeUpdate, as we expect.
- Let's now prevent rendering by returning false:
public shouldComponentUpdate(nextProps: {}, nextState: IState) { console.log("shouldComponentUpdate", ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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