freeCodeCamp/guide/english/certifications/front-end-libraries/react/use-array-map-to-dynamically-render-elements/index.md

title
Use Array.map() to Dynamically Render Elements

Use Array.map() to Dynamically Render Elements

Hint 1:

Define the two states as a JavaScript object.

{object: state, object: state}

Hint 2:

You need .map() to generate a line for every object in the array.

this.state.toDoList.map(i => <li>{i}</li>);

Solution:

Once you add the map function, you will notice that it will generate a <li> for every item you put in the list.

const textAreaStyles = {
  width: 235,
  margin: 5
};

class MyToDoList extends React.Component {
  constructor(props) {
    super(props);
    // change code below this line
    this.state = {
      userInput: '',
      toDoList: []
    }
    // change code above this line
    this.handleSubmit = this.handleSubmit.bind(this);
    this.handleChange = this.handleChange.bind(this);
  }
  handleSubmit() {
    const itemsArray = this.state.userInput.split(',');
    this.setState({
      toDoList: itemsArray
    });
  }
  handleChange(e) {
    this.setState({
      userInput: e.target.value
    });
  }
  render() {
    const items = this.state.toDoList.map(i => <li>{i}</li>); // change code here
    return (
      <div>
        <textarea
          onChange={this.handleChange}
          value={this.state.userInput}
          style={textAreaStyles}
          placeholder="Separate Items With Commas" /><br />
        <button onClick={this.handleSubmit}>Create List</button>
        <h1>My "To Do" List:</h1>
        <ul>
          {items}
        </ul>
      </div>
    );
  }
};