var MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver;

​

var editor = document.querySelector('#editor');

​

var textinputcount = document.querySelector('#textinputcount');

​

var observer = new  MutationObserver(function(mutations){ mutations.forEach(function(mutation){

    if(mutation.type == "characterData") {

    var newValue = mutation.target.textContent;

      textinputcount.innerHTML = "还可以输入"+(1000 - newValue.length+"字");

    }

  });

});

​

observer.observe(editor, {

  childList: true,

  attributes: true,

  characterData: true,

  characterDataOldValue: true,

  subtree: true

});

​

​