計算click（）函數的使用次數

Question

我想知道click（）函數被使用了多少次並記錄了但是我總是得到名為“undefined”或“NaN”的錯誤

 var sleep = 1000; var run = setInterval(function() { var span = document.getElementsByTagName("span"); for (var i = 0; i < span.length; i++) { if (span[i].textContent != "danger") { var jump = document.getElementsByClassName("jump")[0].click(); console.log(jump++); } else { clearInterval(run); } } }, sleep); 

 <span>Danger</span> <button type="button" class="jump">Click</button> 

Answer 1

您需要定義跳轉而不是為其分配按鈕
另外，我建議使用querySelector（All）而不是getElementsByClass / TagName

 var sleep = 1000, jump=0, jumpBut = document.querySelector(".jump"); var run = setInterval(function() { // move this var outside the loop if the spans never change in number var span = document.querySelectorAll("span"); for (var i = 0; i < span.length; i++) { if (span[i].textContent != "danger") { jumpBut.click(); console.log(jump++); } else { clearInterval(run); } } }, sleep); 

 <span>Danger</span> <button type="button" class="jump">Click</button> 

但請嘗試這樣做 - 向按鈕添加一個click事件監聽器並將其添加到計數器中

 var sleep = 1000, jump=0, jumpBut=document.querySelector(".jump"); jumpBut.addEventListener("click",function() { jump++, console.log(jump) }) var run = setInterval(function() { var span = document.querySelectorAll("span"); for (var i = 0; i < span.length; i++) { if (span[i].textContent != "danger") { jumpBut.click(); } else { clearInterval(run); } } }, sleep); 

 <span>Danger</span> <button type="button" class="jump">Click</button> 

Answer 2

你需要一個計數器變量！ 此外，每次調用間隔時都不必使用getElementsByTagName ，除非DOM元素不斷變化。

var sleep = 1000;
var counter = 0;
var spans = document.getElementsByTagName("span");
var jump = document.getElementsByClassName("jump")[0];

var run = setInterval(function(){        
    for (var i =0; i< spans.length; i++) {
        if (spans[i].textContent != "danger") {
            jump.click();
            counter++;
            console.log(counter);
       } else {
            clearInterval(run);
       }
    }
}, sleep);