console
function sample1_func() {
var text_area = document.getElementById("sample1_desc");
var a, b;
while (isNaN(a)) a = Number(prompt("请输入第一个数字"));
while (isNaN(b)) b = Number(prompt("请输入第二个数字"));
text_area.innerHTML += a + "+" + b + "=" + (a + b) + "<br>";
}
var obj = document.getElementById("sample1");
obj.onclick = sample1_func;
<p>HTML <b>内容</b>展示:<span>请点击我...</span></p>
<p>CSS <b>样式</b>展示:<span class="sample1">请点击我...</span></p>
<p>JavaScript <b>行为</b>展示:<span class="sample1" id="sample1">请点击我...</span></p>
<p id="sample1_desc"></p>
.sample1 {
color: #339999;
text-decoration: underline;
cursor:pointer;
border: 3px solid red;
}
#sample1_desc {
width: 40%;
height: 100px;
border: 5px solid #000;
border-radius: 20px;
overflow: auto;
text-indent: 0;
padding-left: 2em;
}