- 时间:2021-02-05 20:57 编辑: 来源: 阅读:
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摘要:javascript基础第一章 JavaScript与用户端
一 页面输出
1.头部文件
[url=http://www.1sucai.cn]
9.判断分支
<script>
window.onload = initAll;
function initAll() {
document.getElementById("Lincoln").onclick = saySomething;
document.getElementById("Kennedy").onclick = saySomething;
document.getElementById("Nixon").onclick = saySomething;
}
function saySomething() {
switch(this.id) {
case "Lincoln":
alert("Four score and seven years ago...");
break;
case "Kennedy":
alert("Ask not what your country can do for you...");
break;
case "Nixon":
alert("I am not a crook!");
break;
default:
}
}
</script>
<form action="#">
<input type="button" id="Lincoln" value="Lincoln" />
<input
type="button" id="Kennedy" value="Kennedy" />
<input type="button" id="Nixon"
value="Nixon" />
</form>
10.异常捕获
window.onload = initAll;
function initAll() {
var ans = prompt("输入参数:","");
try {
if (!ans || isNaN(ans) || ans<0) {
throw new Error("输入为非数");
}
alert("根号" + ans + " 是 " + Math.sqrt(ans));
}
catch (errMsg) {
alert(errMsg.message);
}
}