textbox empty check using javascript

Question

i have a jsp page. now i want to fill some information here and click the submit button. but i need to check that the textbox are not empty. how to do?

Answer 1

Canonical without using frameworks with added trim prototype for older browsers

<html>
<head>
<script type="text/javascript">
if (!String.trim) {String.prototype.trim = function() {return this.replace(/^\s+|\s+$/g, "");};}
function validate(theForm) { // passing the form object
  var val = theForm.textField1.value;
  if (val==null || val.trim()=="") { 
    alert('Please enter something');
    theForm.textField1.focus();
    return false; // cancel submission
  }
  return true; // allow submit
}
</script>
</head>
<body>
<form onsubmit="return validate(this)">
<input type="text" name="textField1" value="" /><br/>
<input type="submit" />
</form>
</body>
</html>

Answer 2

Hey DUDE,

Use this scrip, It will help you a lot. I have given few of the explanation with line of code.

<script Language="JavaScript">
<!-- 
function Blank_TextField_Validator()
{
// Check the value of the element named text_name from the form named text_form
if (text_form.text_name.value == "")
{
  // If null display and alert box
   alert("Please fill in the text field.");
  // Place the cursor on the field for revision
   text_form.text_name.focus();
  // return false to stop further processing
   return (false);
}
// If text_name is not null continue processing
return (true);
}
-->
</script>
<form name="text_form" method="get" action="#" 
onsubmit="return Blank_TextField_Validator()">
<input type="text" name="text_name" >
<input type="submit" value="Submit">
</form>

All the Best !!!

Answer 3

Using regexp: \S will match non whitespace character:anything but not a space, tab or new line. If your string has a single character which is not a space, tab or new line, then it's not empty. Therefore you just need to search for one character: \S

<HTML>
<HEAD>
<TITLE>Test</TITLE>

<STYLE>

</STYLE>

<script>
function checkvalue() { 
mystring=document.getElementById('myString').value; 
if(!mystring.match(/\S/)){
alert ('Empty value is not allowed');
return false;
}else{
 alert ("correct input");
 return true;
}
}
</script>

</HEAD>
<BODY>
<form onsubmit="return checkvalue(this)">
<input name="myString" type="text" value='' id="myString">
<input type="submit" value="check value" />
</form>
</BODY>
</HTML>