Welcome to ShenZhenJia Knowledge Sharing Community for programmer and developer-Open, Learning and Share
menu search
person
Welcome To Ask or Share your Answers For Others

Categories

Learning React from the docs and came across this example:

class Square extends React.Component {
  constructor() {
    super();
    this.state = {
      value: null,
    };
  }
  ...
}

According to Mozilla, super allows you to use this in the constructor. Is there any other reason to use a stand alone super (I know super allows you to access parent class's methods as well) but with React is there any other use case of just calling super() by itself?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
thumb_up_alt 0 like thumb_down_alt 0 dislike
263 views
Welcome To Ask or Share your Answers For Others

1 Answer

super() will calls the constructor of its parent class. This is required when you need to access some variables from the parent class.

In React, when you call super with props. React will make props available across the component through this.props. See example 2 below

without super()

class A {
  constructor() {
    this.a = 'hello'
  }
}

class B extends A {
  constructor(){
    console.log(this.a) //throws an error
  }
}

console.log(new B())

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
thumb_up_alt 0 like thumb_down_alt 0 dislike
Welcome to ShenZhenJia Knowledge Sharing Community for programmer and developer-Open, Learning and Share
...