javascript第一次打開後禁用事件偵聽器

Question

如何禁用此事件偵聽器，以便它只觸發一次？

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

設置一個布爾值，第一次執行後假，這將在每次函數運行前應檢查：

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


     doTouchEvent = false; 
    } 
};