javascript第一次打开后禁用事件侦听器

Question

如何禁用此事件侦听器，以便它只触发一次？

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

设置一个布尔值，第一次执行后假，这将在每次函数运行前应检查：

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


     doTouchEvent = false; 
    } 
};