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How to get form in js_javascript skills

WBOY
WBOYOriginal
2016-05-16 16:00:392153browse

The example in this article describes the method of obtaining form in js. Share it with everyone for your reference. The details are as follows:

Let’s look at the following code first: 

<html> 
<head> 
<scirpy> 
window.onload=function(){ 
   var f1=document.f1; 
   var f2=document.forms[1]; 
 alert(f2.id); 
  var f3=document.forms['f1']; 
} 
</script> 
</head> 
<body> 
<form id="f1" value="f1"></from> 
<from id="f2" value="f2"></form> 
</body> 
</html>

Operation form: 

<html> 
 <head> 
 <script> 
  function checkform(f){ 
  var uname=f.username; 
  var pwd=f.password; 
  if(uname.value.length<4){ 
  alert('用户长度必须大于4')； 
  return false; 
  } 
  if(pwd.value.length!=6){ 
  alert('用户密码必须大于 6位'); 
  return false; 
  } 
  return true; 
  } 
 </script> 
 </head> 
 <body> 
 <form id="f1" name="f1" method="post" action=""
 onsubmit="return checkform(this)"> 
   <input name="username" value="" /></br> 
  <input name="password" value="" /></br> 
  <input type="button" value="提交" />  
 </form> 
 </body> 
</html>

Three ways to operate forms with js:

1. Use the index of the form in the document or the name attribute of the form to reference the form

Copy code The code is as follows:
document.forms[i] //Get the i-th item in the page Form
document.forms[fromName] //Get the form of the corresponding name in the page

2. Use the id attribute of the form

Copy code The code is as follows:
document.getElementById(formId);

3.

Copy code The code is as follows:
document.formName;//The most commonly used method

I hope this article will be helpful to everyone’s JavaScript programming design.

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