JSFiddle - React, Tailwind, and code Playground

JavaScript

window.main = {
    object: {
        doSomething: function(){
            alert('Called');
       }
    }
}

function callFromString(aString) {
  var parts = aString.split(".");
  var obj = window;
  for (var i = 0; i < parts.length - 1; i++) {
    obj = obj[parts[i]];
    if (!obj)
      return;
  }
  // strip () at the end of parts[parts.length - 1] if they are present
  if (obj[parts[parts.length - 1]])
    obj[parts[parts.length - 1]]();
}

callFromString("main.object.doSomething");