React - getting a component from a DOM element for debugging

Question

For the purposes of debugging in the console, is there any mechanism available in React to use a DOM element instance to get the backing React component?

This questi

Answer 1

I've adapted @Venryx's answer with a slightly adapted ES6 version that fit my needs. This helper function returns the current element instead of the _owner._instance property.

getReactDomComponent(dom) {
  const internalInstance = dom[Object.keys(dom).find(key =>
    key.startsWith('__reactInternalInstance$'))];
  if (!internalInstance) return null;
  return internalInstance._currentElement;
}

Answer 2

I've just read through the docs, and afaik none of the externally-exposed APIs will let you directly go in and find a React component by ID. However, you can update your initial React.render() call and keep the return value somewhere, e.g.:

window.searchRoot = React.render(React.createElement......

You can then reference searchRoot, and look through that directly, or traverse it using the React.addons.TestUtils. e.g. this will give you all the components:

var componentsArray = React.addons.TestUtils.findAllInRenderedTree(window.searchRoot, function() { return true; });

There are several built-in methods for filtering this tree, or you can write your own function to only return components based on some check you write.

More about TestUtils here: https://facebook.github.io/react/docs/test-utils.html

Answer 3

Here is a small snippet i'm currently using.

It works with React 0.14.7.

Gist with the code

let searchRoot = ReactDom.render(ROOT, document.getElementById('main'));

var getComponent = (comp) => comp._renderedComponent ? getComponent(comp._renderedComponent) : comp;

var getComponentById = (id)=> {
  var comp = searchRoot._reactInternalInstance;
  var path = id.substr(1).split('.').map(a=> '.' + a);
  if (comp._rootNodeID !== path.shift()) throw 'Unknown root';
  while (path.length > 0) {
    comp = getComponent(comp)._renderedChildren[path.shift()];
  }
  return comp._instance;
};

window.$r = (node)=> getComponentById(node.getAttribute('data-reactid'))

to run it, open Devtools, highlight an element you want to examine, and in the console type : $r($0)

Answer 4

v15 and v16 compatible with svg, html, comment, text nodes

/* Node extends text, svg, html
 usage for node $0:
    $0.reactive // returns [node, parentNode, rootNode]
    $0.react.props // {any:'prop'}
    $0.react.setState(...) // update
 */
Object.defineProperties(Node.prototype, {
    _react: {writable:true, value:''}
    ,reactKey: {
        get: function(){
            let symbol = this._react;
            if(symbol){ return symbol; }
            // v15, v16 use a string as key, probably a real symbol in the future
            symbol = Object.keys(this).find(key => key.startsWith('__reactInternalInstance$'));
            return Node.prototype._react = symbol || '';
        }
    }
    // try to find the props/state/React-instance
    ,react: {
        get: function(){
            let react = this[ this.reactKey ] || null;
            let $0;
            if(react){
                $0 = react._currentElement;
                if($0){ // v15
                    if($0._owner){
                        return $0._owner._instance;
                    }else{
                        return $0;
                    };
                }
                $0 = react.return;
                if($0){ // v16
                    // develop mode only: return react._debugOwner.stateNode
                    // both develop and prod modes:
                    return $0.stateNode
                }
            }else if(this._reactRootContainer){
                // v16 _internalRoot === _internalRoot.current.stateNode
                return this._reactRootContainer._internalRoot;
            }
            return react;
        }
    }
    // make a list of self, ancestors that make up this branch of the tree
    ,reactive: {
        get: function(list=[]){
            let $0 = this;
            while($0 && !$0[ $0.reactKey ] && !$0._reactRootContainer ){
                $0 = $0.previousSibling;
            };
            if($0 && ($0[$0.reactKey] || $0._reactRootContainer)){
                list.push($0);
            };
            $0 = this;
            while($0 = $0.parentNode){
                if($0[ $0.reactKey ] || $0._reactRootContainer){
                    list.push($0);
                }
            };
            return list;
        }
    }
});

Answer 5

In case someone is struggling like me to access React component/properties from a chrome extension, all of the above solutions are not going to work from chrome extension content-script. Rather, you'll have to inject a script tag and run your code from there. Here is complete explanation: https://stackoverflow.com/a/9517879/2037323

Answer 6

Here you go. This supports React 16+

window.findReactComponent = function(el) {
  for (const key in el) {
    if (key.startsWith('__reactInternalInstance$')) {
      const fiberNode = el[key];

      return fiberNode && fiberNode.return && fiberNode.return.stateNode;
    }
  }
  return null;
};