JavaScrip——简单练习（输出方式，简单表单验证）

<script>
//输出方式
document.write(Date());//获取当前时间
document.write(1);
document.write("<p>你好</p>");//直接输内容
document.getElementById("nihao").innerHTML;//通过获取id
document.getElementById("nihao").innerHTML="走";
//alert("你好");//alert输出
 
</script>
 
<form id="f1" name="f1" onsubmit="return checkform()">
用户名：<input type="text" name="username" value="" />
 
<input type="submit" value="提交" />
</form> 
 
<script>
function checkform()
{
    var f11=document.f1.username.value.length;
    if(f11>4)
    {alert("小于4");
     return false;}
    }
</script>
 
<form onsubmit="return validation()">
    <span>账号</span><input type="text" id="no" /><br>
    <span>密码</span><input type="text" id="pwd" /><br>
    <button type="submit">提交</button>
</form>
<script>
function validation() {
    var no = document.getElementById("no").value;
    var pwd = document.getElementById("pwd").value;
    if(no == "") {
        alert("账号不为空!");
        return false;
    }
 
if(pwd == "") {
        alert("密码不为空!");
        return false;
    }
}
</script>
 
<form name=a onsubmit="return test()">
<textarea name="b"  cols="40"  wrap="VIRTUAL" rows="6"></textarea>
<input type="submit" name="Submit" value="check">
</form>
<script>
function test()
{
if(document.a.b.value.length>10)
{
alert("不能超过10个字符！");
document.a.b.focus();
return false;
}
}
</script>

结果：静态