我完全不知道从哪里开始，我将如何创建一个倒数按钮，以便每次单击我的按钮时，它都会打印出全局变量，并在innerHTML中将其减小1，当它达到0时，它将显示BOOM ？
我知道我必须在外部声明变量，但不确定之后该怎么做
JS：
var i = 20
function myFunction()
{
i = i--; // the value of i starting at 20
}
HTML：
<!DOCTYPE html>
<html lang="en">
<head>
<!-- link to external JS file. Note that <script> has an
end </script> tag -->
<meta charset="utf-8">
<title> Task 6 </title>
<link href="style.css" type="text/css" rel="stylesheet">
<script src="task6.js" type="text/javascript"></script>
</head>
<body>
<!-- Create a paragraph with id mydata -->
<div id="box">
<p id="mydata"> Count Down </p>
<p> <button onclick="myFunction();"> Click </button></p>
</div>
</body>
</html>
最佳答案
我尝试了这段代码并正常工作
var i = 20;
function myFunction() {
myData = document.getElementById("mydata");
i = i - 1;
myData.textContent = i;
if(i <= 0) {//with <=0 the user if click again,after zero he sees only BOOM
myData.textContent = "BOOM!"
}
}
HTML代码
<!DOCTYPE html>
<html lang="en">
<head>
<!-- link to external JS file. Note that <script> has an
end </script> tag -->
<meta charset="utf-8">
<title> Task 6 </title>
<link href="style.css" type="text/css" rel="stylesheet">
<script src="task6.js" type="text/javascript"></script>
</head>
<body>
<!-- Create a paragraph with id mydata -->
<div id="box">
<p id="mydata"> Count Down </p>
<p> <button onclick="myFunction();"> Click </button></p>
</div>
<!DOCTYPE html>
<html lang="en">
<head>
<!-- link to external JS file. Note that <script> has an
end </script> tag -->
<meta charset="utf-8">
<title> Task 6 </title>
<link href="style.css" type="text/css" rel="stylesheet">
<script type="text/javascript">
var i = 20;
function myFunction() {
var myData = document.getElementById("mydata");
i = i - 1;
myData.textContent = i;
if(i <= 0) {
myData.textContent = "BOOM!"
}
}
</script>
</head>
<body>
<!-- Create a paragraph with id mydata -->
<div id="box">
<p id="mydata"> Count Down </p>
<p> <button onclick="myFunction();"> Click </button></p>
</div>
</body>
</html>关于javascript - 倒数计时答题器-JS，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/52936195/