How to display each item in an array in React JS?

Question

I'm new to React and programing in general and I'm having trouble writing code that return each element in an array, in React JS. the whole code is below:

import React from 'react'

const App = () => {
  const course = {
    name: 'Half Stack application development',
    parts: [
      {
        name: 'Fundamentals of React',
        exercises: 10
      },
      {
        name: 'Using props to pass data',
        exercises: 7
      },
      {
        name: 'State of a component',
        exercises: 14
      }
    ]
  }
  const Header = (props) => {
    return (
      <h1>{props.course.name}</h1>
    )
  }
  
  const Content = (props) => {
    const lisItem = props.course.parts.map((part =>
      <li>{props.course.parts.name}</li>
    ))
    return (
      <ul>{lisItem}</ul>
    )
  }

  return (
    <div>
      <Header course={course}/>
      <Content course={course}/>
    </div>
  )
}

export default App

Right now it half-works: I can display 3 bullet points (match with numbers of parts) but cannot display the name of the part itself.

Also I would like to clarify the out put a wanted is the course's name and each name of the parts be displayed.

Any help would be appreciated. Thank you very much.

gmoniava · Accepted Answer · 2021-10-29 16:37:47Z

2

You are not using map correctly. It should be like this:

const lisItem = props.course.parts.map((part) => <li>{part.name}</li>);

You were ignoring each part given to you by map. Check docs of map.

Also I see now you were defining the two components Header and Content inside the App component, that is not good practice (due to reconciliation), move their definition outside of App:

import React from "react";

const Header = (props) => {
  return <h1>{props.course.name}</h1>;
};

const Content = (props) => {
  const lisItem = props.course.parts.map((part) => <li>{part.name}</li>);
  return <ul>{lisItem}</ul>;
};

const App = () => {
  const course = {
    name: "Half Stack application development",
    parts: [
      {
        name: "Fundamentals of React",
        exercises: 10,
      },
      {
        name: "Using props to pass data",
        exercises: 7,
      },
      {
        name: "State of a component",
        exercises: 14,
      },
    ],
  };

  return (
    <div>
      <Header course={course} />
      <Content course={course} />
    </div>
  );
};

edited Oct 29, 2021 at 16:37

answered Oct 29, 2021 at 16:19

gmoniava

28.9k9 gold badges61 silver badges101 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

trang nguyen Over a year ago

thank you. i didn't understand the map function fully. and thank you for the advice constructing the code.

mcarn · Accepted Answer · 2021-10-29 16:19:36Z

0

Your .map( part => ...) iterates props.course.parts, the part inside the map function is a single item of the list.

Check MDN for more info https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map

answered Oct 29, 2021 at 16:19

mcarn

766 bronze badges

Collectives™ on Stack Overflow

How to display each item in an array in React JS?

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related