2020-4-5

放羊的星星，，

于 2020-04-06 05:47:32 发布

阅读量142

点赞数

本文链接：https://blog.youkuaiyun.com/weixin_44849258/article/details/105337788

版权

题目一：

<!DOCTYPE html>
<html>
<head>
<meta charset=" utf-8">
<script> 
window.onload=function(){
  let txt=document.getElementById("txt");
  let st=document.getElementById("st");
  let form=document.forms[0];
  form.onsubmit=function(){
    if(txt.value==""){
      alert("请先写一些内容");
      txt.focus();
      return false;
    }
  }
  document.onkeydown = function(ev){
    if(ev.keyCode==13&&document.activeElement === form) {
      form.submit();
    }
  }
}
</script> 
</head> 
<body> 
<form action="#" id="fm">
  <input type="text" id="txt" name="txt">
  <input type="submit" id="st" name="st">
</form>
</body> 
</html>