第一次点击后，javascript禁用事件监听器

Question

How do I disable this event listener so that it only fires once?

document.getElementById('element').ontouchmove = function (e) 
{   
  DISABLE HERE
  do something that should only happen once
};

Answer 1

document.getElementById('element').ontouchmove = function (e) {   
  this.ontouchmove = null;

  // Do something here.
};

Answer 2

Set a Boolean to false after first execution, which will be checked each time before the function runs:

var doTouchEvent = true;
document.getElementById('element').ontouchmove = function (e) 
{   
   if(doTouchEvent){
      DISABLE HERE
      do something that should only happen once


      doTouchEvent = false;
   }
};