How to check if a textbox is empty using javascript

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I have a jsp page with some TextBoxes. Now I want to fill them with some information and click the submit button. But I need to check whether this TextBox is empty or not.

How can I do this?

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

JavaScript:

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

HTML:

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

JavaScript : HTML form - Checking for non empty, Checking non empty field. Javascript function to check whether a field is empty or not // If the length of the element's string is 0 then display helper message function required(inputtx) { if (inputtx.value.length == 0) { alert("message"); return false; } return true; } Flowchart: HTML Code <! Events to validate the input. If you want to validate the input when a user types into the field, you can use the input event. const input = document.querySelector('input') input.addEventListener('input', evt => { // Validate input }) If you want to validate the input when a user submits a form, you can use the submit event.

Canonical without using frameworks with added trim prototype for older browsers

<html>
<head>
<script type="text/javascript">
// add trim to older IEs
if (!String.trim) {
  String.prototype.trim = function() {return this.replace(/^\s+|\s+$/g, "");};
}

window.onload=function() { // onobtrusively adding the submit handler
  document.getElementById("form1").onsubmit=function() { // needs an ID
    var val = this.textField1.value; // 'this' is the form 
    if (val==null || val.trim()=="") { 
      alert('Please enter something');
      this.textField1.focus();
      return false; // cancel submission
    }
    return true; // allow submit
  }
}
</script>
</head>
<body>
<form id="form1">
  <input type="text" name="textField1" value="" /><br/>
  <input type="submit" />
</form>
</body>
</html>

Here is the inline version, although not recommended I show it here in case you need to add validation without being able to refactor the code

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
}

passing the form object in (this)

<form onsubmit="return validate(this)">
  <input type="text" name="textField1" value="" /><br/>
  <input type="submit" />
</form>

How to check if JavaScript Object is empty (Example), How do you check whether the textbox is empty or not in JavaScript? In above script, function Empty will check that the HTML input that is being send to the server has something in it. This is done with the help of built in properties of JavaScript strings; take the value of input textbox trim it and then check for empty string. If value is not empty show the successful message.

Using this JavaScript will help you a lot. Some explanations are given within the code.

<script type="text/javascript">
    <!-- 
        function Blank_TextField_Validator()
        {
        // Check whether the value of the element 
        // text_name from the form named text_form is null
        if (!text_form.text_name.value)
        {
          // If it is 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>

Checking if an input is empty with JavaScript, with myArray. length, but on the other hand, objects do not work that way. Alternatively, you can write the isEmpty function on the Object prototype. Step 2) Add JavaScript: If an input field (fname) is empty, this function alerts a message, and returns false, to prevent the form from being submitted: Example

You can also check it using jQuery.. It's quite easy:

<html>
    <head>
        <title>jQuery: Check if Textbox is empty</title>
        <script type="text/javascript" src="js/jquery_1.7.1_min.js"></script>
    </head>
    <body>
        <form name="form1" method="post" action="">
            <label for="city">City:</label>
            <input type="text" name="city" id="city">
        </form>
        <button id="check">Check</button>
        <script type="text/javascript">
             $('#check').click(function () {
                 if ($('#city').val() == '') {
                     alert('Empty!!!');
                 } else {
                     alert('Contains: ' + $('#city').val());
                 }
             });                
        </script>
    </body>
</html>

[RESOLVED] Checking if text box is empty?, If you want to validate the input when a user submits a form, you can use the submit event. Make sure you prevent the default behavior with  Check if text field input is a number: 35. Call select method to highlight the text field: 36. Change the text value in text box into upper case: 37. Getting and Setting a Text Object's value Property: 38. Feed value from array to text box

Whatever method you choose is not freeing you from performing the same validation on at the back end.

How To Add Validation For Empty Input Field with JavaScript, can check if the text box named "title" was empty (form name is form) and of it was it <script language="javascript"> function DoSubmit () { if  When a user loads my page there is a contact form and they have to fill in all text boxes. If they click submit and a text box is empty above the text box new text will appear telling the user that they forget to fill in that text box. Heres the code I'm currently using:-.

How to check whether an input text box is empty with JavaScript , Step 2) Add JavaScript: If an input field (fname) is empty, this function alerts a message, and returns false, to prevent the form from being submitted:  I have a jsp page with some TextBoxes. Now I want to fill them with some information and click the submit button. But I need to check whether this TextBox is empty or not. How can I do this?

how to write a javascript function to check the value of textbox, To check if input text box is empty using jQuery, you can use the .val() method. It returns value of an form element, and undefined on an empty collection. jQuery  Most often, the purpose of data validation is to ensure correct user input. Validation can be defined by many different methods, and deployed in many different ways. Server side validation is performed by a web server, after input has been sent to the server. Client side validation is performed by a web browser, before input is sent to a web server.

Check if a text field is empty : TextField « Form Control « JavaScript , when ever add button is click i need to check the value in the textbox and 1. if textbox 1 is empty and textbox2 and textbox 3 are full i need to  Javascript function to check whether a field is empty or not At first the function required() will accept the HTML input value through inputtx parameter. After that length property of string, object is used to get the length of the said parameter. If the length of value.inputtx is 0 then it returns false otherwise true.

Comments
  • @mplungjan: this data is cached, have a bit of patience. It'll catch up in about 15 mins.
  • +1 that prevented from redirecting to another page and solvd my problem..cheers..
  • @dreamonic - here you indented code that needed it, but in my opinion did not go far enough. The function and if's content are left aligned - no need to indent the code under the script tag and waste 12 spaces
  • @mplungjan That's a matter of opinion. I should have indented the JavaScript function though -- like the last edit I've committed.
  • @Dreamonic I fail to see why you would indent my code so far it cannot be read without scrolling. I indented it the way I prefer to indent it, for maximum visibility and still indented.
  • Couldn't resist, could you? :) Well, since we're gonna do this now, I'll just leave this here: meta.stackexchange.com/questions/183169
  • No problem. Perhaps he will read it - too bad it cost me 10 meta rep
  • Even now, not all of your code can be read without scrolling. I genuinely don't think there's anything wrong with trying to upgrade readability and code clarification.
  • Actually, the code you cannot read is a paste only piece of trim. The window.onload code and the comments to the right were the ones I was annoyed about - Just please leave my code alone and if you must, indent code that needs it.
  • 1) Not all browsers will understand text_form - you should use document.text_form 2) pass the form to the function is far safer and simpler 3) what's with the "DUDE" ? Could be a DUDETTE