A basic JSON select function

JSONselect.js

// obj: JSON object
// selector: The path to the data you want to extract
function JSONselect(obj, selector) {
   var levels = selector.split('.')
   var object = obj;
   levels.map(function(path) {
     console.log(path)
     object = object[path];
   })
   return object;
}

var myJson = {
  name: "my object",
  companies: [
    {
      name: "First company",
      address: "Somewhere"
    },
    {
      name: "Second company",
      address: "Somewhere else"
    }
  ],
  age: 23
};

JSONselect(myJson, 'companies.0.name') //  => "First company"

JSONselect(myJson, 'age') //  => 23