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Why there can be multiple console output with one console.log() in ReactJS ?

12/11/2022
2 min read

In ReactJS, a single console.log() statement can produce multiple outputs in the console because React uses a virtual DOM (Document Object Model) to render and update the user interface. When a console.log() statement is executed, it may output multiple elements from the virtual DOM, depending on how the React components are structured and how the code is written.

For example, if a console.log() statement is called within a React component that contains multiple child components, each of those child components may be output to the console individually. Additionally, if the console.log () statement is called within a React component that updates over time, it may output multiple versions of the component as it changes.

In order to avoid this behavior and only output a single element from the virtual DOM, you can use the React.Children utility to extract the specific child component that you want to log, or you can use the console.dir() method, which outputs a tree-like representation of the DOM element, rather than individual elements. For example:

import React from 'react';

class MyComponent extends React.Component {
  render() {
    console.log(React.Children.only(this.props.children));
    // or:
    console.dir(this.props.children);

    return (
      <div>
        {this.props.children}
      </div>
    );
  }
}

In this code, the console.log() statement will only output a single child element from the this.props.children prop, rather than multiple elements. This can help to make your debug output more readable and easier to understand.

Happy Coding!