conveyal/modeify

/**
 * dependencies
 */

var has = require('../../has-transitions/1.0.0')
  , emitter = require('css-emitter-component')
  , once = require('once-component');

/**
 * Transition support.
 */

var supported = has();

/**
 * Export `after`
 */

module.exports = after;

/**
 * Invoke the given `fn` after transitions
 *
 * It will be invoked only if the browser
 * supports transitions __and__
 * the element has transitions
 * set in `.style` or css.
 *
 * @param {Element} el
 * @param {Function} fn
 * @return {Function} fn
 * @api public
 */

function after(el, fn){
  if (!supported || !has(el)) return fn();
  emitter(el).bind(fn);
  return fn;
};

/**
 * Same as `after()` only the function is invoked once.
 *
 * @param {Element} el
 * @param {Function} fn
 * @return {Function}
 * @api public
 */

after.once = function(el, fn){
  var callback = once(fn);
  after(el, fn = function(){
    emitter(el).unbind(fn);
    callback();
  });
};