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Comments (3)

erikasby avatar erikasby commented on May 21, 2024

Added a couple of more debuggers.

Result:
Test > Bar1 > Ex1.render() > Ex2.render() > Ex2.componentDidMount() > Ex1 > Ex2.componentDidMount()

Further investigation is needed and maybe someone can explain if this is intentional behavior.

Click for code w/ added debuggers
import React, { useRef, Component, forwardRef } from "react";

class Ex1 extends Component {
  render() {
    const { innerRef, children } = this.props;

    debugger;
    return (
      <div
        ref={(element) => {
          console.log(
            "This line is called after the componentDidMount in Ex2."
          );
          innerRef.current = element;
          debugger;
        }}
        className="ex1"
      >
        {children}
      </div>
    );
  }
}

class Ex2 extends Component {
  componentDidMount() {
    const { targetRef } = this.props;

    console.log("This line is hit before targetRef is set.");
    console.log(
      "Also it appears to be called twice. Once before the ref is set and once after."
    );

    debugger;
  }

  render() {
    const { innerRef } = this.props;

    debugger;
    return <div className="ex2">I do my own thing</div>;
  }
}

const Bar1 = forwardRef((props, ref) => {
  const { children } = props;

  debugger;
  return <Ex1 innerRef={ref}>{children}</Ex1>;
});

function Test() {
  const targetRef = useRef();

  debugger;
  return (
    <Bar1 ref={targetRef}>
      <Ex2 targetRef={targetRef} />
    </Bar1>
  );
}

export default Test;

from react.

Rishab49 avatar Rishab49 commented on May 21, 2024
  1. I think this is the expected behavior as react renders children before the parent element, hence componentDidMount of Ex2 is called before the ref can be set on the parent i.e; div of Ex1
  2. componentDidMount is called twice because your app must be running in strict mode.

from react.

erikasby avatar erikasby commented on May 21, 2024
  1. I think this is the expected behavior as react renders children before the parent element, hence componentDidMount of Ex2 is called before the ref can be set on the parent i.e; div of Ex1
  2. componentDidMount is called twice because your app must be running in strict mode.

I have somewhat similar conclusion to this. I guess this issue could be closed then @CodeMedic42?

from react.

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