How to pass an array of items in React.js

Question

const ListItem = React.createClass({
  render: function() {
    return <li > {
      this.props.item
    } < /li>;
  }
});

const ToDoList = React.createClass({
  render: function() {

    const todoItems = this.props.items.map(item => {
      return <ListItem item = {
        item
      } > < /ListItem>
    })

    return ( <
      ul > {
        todoItems
      } < /ul>
    );
  }
});

//creating a basic component with no data, just a render function
const MyApp = React.createClass({
  render: function() {
    return ( <
      div className = "well" >
      <
      h1 > Hello < /h1> <
      ToDoList > < /ToDoList> <
      /div>
    );
  }
});

//insert the component into the DOM
ReactDOM.render( < MyApp / > , document.getElementById('container'));



<
div id = "container" > < /div>

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<div id="container"></div>

A ReactJs tutorial says:

If we want to make this a truly extensible list, we could create an array of items, then pass them into props through the ToDoList component, then render out each item. Let's do that now.

How can I pass the array of items in the above code?

pizzarob · Accepted Answer · 2017-05-13 03:16:54Z

38

Data can be passed to components via props.

https://facebook.github.io/react/tutorial/tutorial.html#passing-data-through-props

In your case props would be accessed inside the components via this.props.

<TodoList /> takes a prop called items which is an array. Inside <TodoList /> you can map through that array and return elements.

For example in the render method of your class you would return TodoList with a prop of items:

const myItems = [{ name: 'item 1' }, { name: 'item2' }];
function MyApp() {
    return (
       <TodoList items={myItems} />
    );
}

Then in TodoList you map the items

function TodoList({ items }) {
    return items.map(item => (
        <h1>{item.name}</h1>
    ));
}

answered May 13, 2017 at 3:16

pizzarob

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3 Comments

DarkArtistry Over a year ago

This code makes me understand how i can manupulate it with objects ,, nice :D

Chau Pham Over a year ago

Can you please explain why we have to put curly brackets around items in TodoList function? I tried function TodoList( items ) but it returned errors : items.map is not a function

Pim Over a year ago

@Catbuilts That's just the React/Babel syntax

Gratus D. · Accepted Answer · 2017-05-13 03:12:36Z

1

You just set up an attribute, with the same name

<ToDoList items={myitems} />

answered May 13, 2017 at 3:12

Gratus D.

8778 silver badges23 bronze badges

3 Comments

DarkArtistry Over a year ago

i tried this <ToDoList items=[1,2,3,4]></ToDoList> but it didn't worked

Gratus D. Over a year ago

Can you try <ToDoList items={[1,2,3,4]}></ToDoList>

DarkArtistry Over a year ago

say if i wanted the prop item's array to be [1,2,3,4] how should i edit it ?

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