testscript.js

var mathFieldSpan = document.getElementById('math-field');
var latexSpan = document.getElementById('latex');

var MQ = MathQuill.getInterface(2); // for backcompat
var mathField = MQ.MathField(mathFieldSpan, {
  spaceBehavesLikeTab: true, // configurable
  handlers: {
    edit: function() { // useful event handlers
      latexSpan.textContent = mathField.latex(); // simple API
    }
  }
});