Iframe Resizer (no dependencies) with AMD/global definitions

iframe-resizer.js

(function (root, factory) {
  if (typeof define === 'function' && define.amd) {
      define('iframeResizer', function (iframeResizer) {
          return (root.iframeResizer = factory());
      });
  } else {
      root.iframeResizer = factory();
  }
}(this, function () {  
  return function(msgPrefix, targetOrigin, minFrameHeight,) {
    var timer, frameDefaultOverflow;

    minFrameHeight = minFrameHeight || 250;
    targetOrigin = targetOrigin || '*';

    return {
      start : function() {
        if(!window.postMessage) return;

        var currentHeight = 0,
            bodyNode = document.body,
            frameTopMargin,
            frameBtmMargin;
        
        frameDefaultOverflow = window.getComputedStyle(bodyNode).overflow;
        document.documentElement.style.overflow = 'hidden';
        frameTopMargin = parseInt(window.getComputedStyle(bodyNode).marginTop, 16);;
        frameBtmMargin = parseInt(window.getComputedStyle(bodyNode).marginBottom, 16)

        timer = setInterval(function() {
          var documentHeight = Math.max(
            frameTopMargin + frameBtmMargin + bodyNode.clientHeight,
            minFrameHeight
          );
          if(documentHeight !== currentHeight) {
            window.parent.postMessage(msgPrefix + documentHeight, targetOrigin);
            currentHeight = documentHeight;
          }
        }, 200);
      },
      stop: function() {
        clearInterval(timer);
        document.documentElement.style.overflow = frameDefaultOverflow;
      }
    }
  }
}));

// Initialise
var iframer = iframeResizer('resize', 'http://www.foo.com', 250);

// Start
iframer.start();

// Stop
iframer.stop();

// Using AMD
var iframer = require('iframeResizer')('resize', 'http://www.foo.com', 250);

// Start
iframer.start();

// Receiving messages
window.addEventListener('message', function(event){
   if(event.origin !== 'http://www.foo.com') return;
  // Note: if you included a msgPrefix then you will need to filter this from event.data before applying this    
  document.querySelector('iframe').style.height = event.data + 'px';  
});