Javascript functions that create Facebook and Twitter pop ups for sharing. No APIs are necessary.

socialPopups.js

'use strict';

/**
 * Popup with a Facebook share page without the need of the JS API.
 * @param {string} url URL of the page to share.
 * @param {?number} opt_height Height of the popup.
 * @param {?number} opt_width Width of the popup.
 */
facebookShare = function(url, opt_height, opt_width) {
  var href = url;
  var height = opt_height ? 400;
  var width = opt_width ? 575;
  var left = (window.outerWidth - width) / 2;
  var top = (window.outerHeight - height) / 2;
  var url = 'https://www.facebook.com/sharer/sharer.php?u=' + href;
  var opts = 'status=1' +
      ',width=' + width +
      ',height=' + height +
      ',top=' + top +
      ',left=' + left;
  window.open(url, 'Facebook', opts);
};

/**
 * Creates a popup with a Twitter Tweet dialogue sharing a URL.
 * @param {string} href URL of the page to share.
 * @param {string} text Editable tweet text to include.
 * @param {string} via Twitter user to attribute the URL to.
 * @param {?number} opt_height Height of the popup.
 * @param {?number} opt_width Width of the popup.
 */
twitterShare = function(href, text, via, opt_height, opt_width) {
  var height = opt_height ? 400;
  var width = opt_width ? 575;
  var left = (window.outerWidth - width) / 2;
  var top = (window.outerHeight - height) / 2;
  var url = 'https://twitter.com/share?text=' + text +
          '&url=' + href + '&via=' + via;
  var opts = 'status=1' +
      ',width=' + width +
      ',height=' + height +
      ',top=' + top +
      ',left=' + left;
  window.open(url, 'Twitter', opts);
};