CODEWITHSUNDEEP
reactjs
skidwa
skidwa

Reputation: 123

React Map (key,value) example- need clarity

can anyone tell me what this.state.data.map is doing, it shows key and person, but i dont understand what this is doing.

import React from 'react';

class App extends React.Component {
   constructor() {
      super();
      this.state = {
         data: 
         [
            {
               "id":1,
               "name":"Foo",
               "age":"20"
            },
            {
               "id":2,
               "name":"Bar",
               "age":"30"
            },
            {
               "id":3,
               "name":"Baz",
               "age":"40"
            }
         ]
      }
   }
   render() {
      return (
         <div>
            <Header/>
            <table>
               <tbody>

iam not sure what the below line does.

                {this.state.data.map((person, i) => <TableRow key = {i} 
                     data = {person} />)}
               </tbody>
            </table>
         </div>
      );
   }
}
class Header extends React.Component {
   render() {
      return (
         <div>
            <h1>Header</h1>
         </div>
      );
   }
}
class TableRow extends React.Component {
   render() {
      return (
         <tr>
            <td>{this.props.data.id}</td>
            <td>{this.props.data.name}</td>
            <td>{this.props.data.age}</td>
         </tr>
      );
   }
}
export default App;

iam not sure what this map is doing, what is the person referring to and what is the key.

Upvotes: 0

Views: 1585

Answers (1)

Anand Popat
Anand Popat

Reputation: 143

person is the object inside data array and i is the index of the object inside the array.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map

Upvotes: 1

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