Old-style JS class

js-class.js

function TopologyPreviewer(topologyGraph, presetData, style) {
  // Private variables.
  var privateOne, privateTwo;
  
  // Public variables.
  this.publicOne = 1;
  this.publicTwo = 2;
  
  // Public methods.
  this.preview = function() {
    // ...
  }
  
  // Private methods.
  function updateTree(source) {
    // ...
  }
}