[英]“document.getElementById” is not working
我正在使用HTML和JavaScript編程一組交通信號燈,但遇到了問題。 我創建了一個按鈕,該按鈕應將網站上的文本行更改為數字,但是無論何時單擊它都不會執行任何操作。 我認為這是document.getElementById
腳本存在的問題,因為我認為可能沒有其他問題。 這是我的代碼:
<p id="dummy">PLACEHOLDER</p>
<script>
var imgArray = ["img0", "img1", "img2", "img3"];
imgArray[0] = new Image(300, 150);
imgArray[0].src = "Assets/TrafficLightRedLight.jpg";
imgArray[1] = new Image(300, 150);
imgArray[1].src = "Assets/TrafficLightRedAmberLight.jpg";
imgArray[2] = new Image(300, 150);
imgArray[2].src = "Assets/TrafficLightAmberLight.jpg";
imgArray[3] = new Image(300, 150);
imgArray[3].src = "Assets/TrafficLightGreenLight.jpg";
var counter = 0;
function count(counter){
if (counter =! 3){
counter + 1;
}
else{
counter = 0;
}
document.getElementById("dummy").innerHTML = counter;
}
</script>
<button type="button"
onclick="count">Test_Function</button>
四個問題:
您需要在處理程序中調用 count
:
<button type="button" onclick="count()">Test_Function</button>
counter =! 3
counter =! 3
應該是counter != 3
,否則將其設置為false
counter + 1
不會執行任何操作。 使用counter += 1
或counter++
counter
用作參數-您只修改本地副本。 以上所有修復:
<p id="dummy">PLACEHOLDER</p> <script> var imgArray = ["img0", "img1", "img2", "img3"]; var counter = 0; imgArray[0] = new Image(300, 150); imgArray[0].src = "Assets/TrafficLightRedLight.jpg"; imgArray[1] = new Image(300, 150); imgArray[1].src = "Assets/TrafficLightRedAmberLight.jpg"; imgArray[2] = new Image(300, 150); imgArray[2].src = "Assets/TrafficLightAmberLight.jpg"; imgArray[3] = new Image(300, 150); imgArray[3].src = "Assets/TrafficLightGreenLight.jpg"; function count() { if (counter != 3) { counter++; } else { counter = 0; } document.getElementById("dummy").innerHTML = counter; } </script> <button type="button" onclick="count()">Test_Function</button>
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