How to update props of React Component rendered using ReactDOM.render()

Question

I am trying to integrate react into my angularjs webapp.

In my controller I create the component, which initially has array props that are empty. When the app is done initializing, I want to update the props again. Do I do this by calling ReactDOM.render() again or can I keep a reference to this instance and just do something like updateProps(newProps)?

This is called from my controller:

ReactDOM.render(
    <NavBar
        currencyTabs = {[]}
    />, document.getElementById("navbar-root")
);

And then when the data is done loading i need to update the currencyTabs with a full array ...

I understand how react components props update from parent to child, but I don't quite get how I can do this from plain JS.

Answer 1

There is no magic at work here, you just need to re-render it.

Just wrapper your rendering into a function, eg:

function renderReactNavbar( tabs = [] ) {
  ReactDOM.render(
    <NavBar
        currencyTabs = { tabs }
    />, document.getElementById("navbar-root")
  );

}

and call it after you load / update your data.

Alternatively, you choose to load your data from inside react, which might be a better choice in the long run.

If you have internal state, this might be somewhat harder to handle. You could consider moving to a props only component (but since you don't share any relevant code of your react component, it is hard to say)

A small example of how it could look would be

// the render method, takes a component and props, and renders it to the page
function renderComponent( component, props ) {
  const target = document.querySelector('#container');
  ReactDOM.render( React.createElement( component, props ), target );
}

// gets the tabs from the input field, splits based on ,
function getTabsFromInput() {
  return document.querySelector('#tabs').value.split(',');
}

// small presentational component, shows the tabs and redirects selection changes through a callback
const Tabs = ({ tabs, selectedTab, onSelectionChanged }) => {
  return tabs && <div>{ tabs.map( (tab, key) => {
    return <h1 key={key} className={classNames( { 'active': key === selectedTab } ) } onClick={ () => onSelectionChanged( key ) }>{ tab }</h1>;
  } ) }</div>;
};

// some initiations
window.addEventListener('load', function() {
  // keep a local variable with the data
  let defaultProps = {
    onSelectionChanged: updateSelection,
    selectedTab: 0,
    tabs: getTabsFromInput()
  };

  // handles selection changes
  function updateSelection( newTab ) {
    defaultProps = {...defaultProps, selectedTab: newTab };
    renderComponent( Tabs, defaultProps );
  }

  // adds an event listener for click events to initiate tab changes
  document.querySelector('#updateTabs').addEventListener('click', function() {
    defaultProps = {...defaultProps, tabs: getTabsFromInput() };
    // render on update
    renderComponent( Tabs, defaultProps );
  });

  // initial render
  renderComponent( Tabs, defaultProps );
});

.active {
  background-color: blue;
}

<script id="react" src="https://cdnjs.cloudflare.com/ajax/libs/react/15.6.2/react.js"></script>
<script id="react-dom" src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/15.6.2/react-dom.js"></script>
<script id="classnames" src="https://cdnjs.cloudflare.com/ajax/libs/classnames/2.2.5/index.js"></script><div id="container"></div>
<input type="text" value="tab1,tab2" id="tabs" />
<button id="updateTabs" type="button">Update tabs</button>

Answer 2

Your NavBar component has a state that can be updated using the lifecycle methods. Without you code it is difficult to know for sure, but I think you want something like

class NavBar extends Component {
  state: { currencyTabs: [] }

  componentWillRecieveProps(nextProps) {
    if (this.props.currencyTabs !== nextProps.currencyTabs) {
      this.setState({ currencyTabs: nextProps.currencyTabs })
    }
  }

  render() {
    return (
      <div>
        {this.state.currencyTabs.map(button => (
          <span>{currency}</span>
        )}
      </div>
    )
  }
}

When the currencyTabs prop is changed in your ReactDOM.render method, the component will re-render and the changes will be reflected