JSFiddle - React, Tailwind, and code Playground

JavaScript

var dataModels = [];

dataModels[0] = {
    childNodes: []
};
dataModels[0].childNodes[0] = {
    appId: "foo"
};

dataModels.forEach(function(entry){ 
    entry.childNodes.forEach(function(childrenEntry) { // was missing a )
      console.log(childrenEntry.appId);
    })
})