Javascript – ReactJS call parent method

javascriptreactjs

I'm making my first step in ReactJS and trying to understand communication between parent and children.
I'm making form, so I have the component for styling fields. And also I have parent component that includes field and checking it. Example:

var LoginField = React.createClass({
    render: function() {
        return (
            <MyField icon="user_icon" placeholder="Nickname" />
        );
    },
    check: function () {
        console.log ("aakmslkanslkc");
    }
})

var MyField = React.createClass({
    render: function() {
...
    },
    handleChange: function(event) {
//call parent!
    }
})

Is there any way to do it. And is my logic is good in reactjs "world"? Thanks for your time.

Best Answer

To do this you pass a callback as a property down to the child from the parent.

For example:

var Parent = React.createClass({

    getInitialState: function() {
        return {
            value: 'foo'
        }
    },

    changeHandler: function(value) {
        this.setState({
            value: value
        });
    },

    render: function() {
        return (
            <div>
                <Child value={this.state.value} onChange={this.changeHandler} />
                <span>{this.state.value}</span>
            </div>
        );
    }
});

var Child = React.createClass({
    propTypes: {
        value:      React.PropTypes.string,
        onChange:   React.PropTypes.func
    },
    getDefaultProps: function() {
        return {
            value: ''
        };
    },
    changeHandler: function(e) {
        if (typeof this.props.onChange === 'function') {
            this.props.onChange(e.target.value);
        }
    },
    render: function() {
        return (
            <input type="text" value={this.props.value} onChange={this.changeHandler} />
        );
    }
});

In the above example, Parent calls Child with a property of value and onChange. The Child in return binds an onChange handler to a standard <input /> element and passes the value up to the Parent's callback if it's defined.

As a result the Parent's changeHandler method is called with the first argument being the string value from the <input /> field in the Child. The result is that the Parent's state can be updated with that value, causing the parent's <span /> element to update with the new value as you type it in the Child's input field.