在 jQuery 中如何检查复选框是否被选中？

Question

I need to check the checked property of a checkbox and perform an action based on the checked property using jQuery.

For example, if the age checkbox is checked, then I need to show a textbox to enter age , else hide the textbox.

But the following code returns false by default:

 if ($('#isAgeSelected').attr('checked')) { $("#txtAge").show(); } else { $("#txtAge").hide(); }

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input type="checkbox" id="isAgeSelected"/> <div id="txtAge" style="display:none"> Age is selected </div>

How do I successfully query the checked property?

Answer 1

How do I successfully query the checked property?

The checked property of a checkbox DOM element will give you the checked state of the element.

Given your existing code, you could therefore do this:

if(document.getElementById('isAgeSelected').checked) {
    $("#txtAge").show();
} else {
    $("#txtAge").hide();
}

However, there's a much prettier way to do this, using toggle :

 $('#isAgeSelected').click(function() { $("#txtAge").toggle(this.checked); });

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input type="checkbox" id="isAgeSelected"/> <div id="txtAge" style="display:none">Age is something</div>

Answer 2

Use jQuery's is() function:

if($("#isAgeSelected").is(':checked'))
    $("#txtAge").show();  // checked
else
    $("#txtAge").hide();  // unchecked

Answer 3

Using jQuery > 1.6

<input type="checkbox" value="1" name="checkMeOut" id="checkMeOut" checked="checked" />

// traditional attr
$('#checkMeOut').attr('checked'); // "checked"
// new property method
$('#checkMeOut').prop('checked'); // true

Using the new property method:

if($('#checkMeOut').prop('checked')) {
    // something when checked
} else {
    // something else when not
}

Answer 4

jQuery 1.6+

$('#isAgeSelected').prop('checked')

jQuery 1.5 and below

$('#isAgeSelected').attr('checked')

Any version of jQuery

// Assuming an event handler on a checkbox
if (this.checked)

All credit goes to Xian .

Answer 5

I am using this and this is working absolutely fine:

$("#checkkBoxId").attr("checked") ? alert("Checked") : alert("Unchecked");

Note: If the checkbox is checked it will return true otherwise undefined, so better check for the "TRUE" value.

Answer 6

Use:

<input type="checkbox" name="planned_checked" checked id="planned_checked"> Planned

$("#planned_checked").change(function() {
    if($(this).prop('checked')) {
        alert("Checked Box Selected");
    } else {
        alert("Checked Box deselect");
    }
});

 $("#planned_checked").change(function() { if($(this).prop('checked')) { alert("Checked Box Selected"); } else { alert("Checked Box deselect"); } });

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script> <input type="checkbox" name="planned_checked" checked id="planned_checked"> Planned

Answer 7

Since jQuery 1.6, the behavior of jQuery.attr() has changed and users are encouraged not to use it to retrieve an element's checked state. Instead, you should use jQuery.prop() :

$("#txtAge").toggle(
    $("#isAgeSelected").prop("checked") // For checked attribute it returns true/false;
                                        // Return value changes with checkbox state
);

Two other possibilities are:

$("#txtAge").get(0).checked
$("#txtAge").is(":checked")

Answer 8

This worked for me:

$get("isAgeSelected ").checked == true

Where isAgeSelected is the id of the control.

Also, @karim79's answer works fine. I am not sure what I missed at the time I tested it.

Note, this is answer uses Microsoft Ajax, not jQuery

Answer 9

If you are using an updated version of jquery, you must go for .prop method to resolve your issue:

$('#isAgeSelected').prop('checked') will return true if checked and false if unchecked. I confirmed it and I came across this issue earlier. $('#isAgeSelected').attr('checked') and $('#isAgeSelected').is('checked') is returning undefined which is not a worthy answer for the situation. So do as given below.

if($('#isAgeSelected').prop('checked')) {
    $("#txtAge").show();
} else {
    $("#txtAge").hide();
}

Hope it helps :)- Thanks.

Answer 10

Use:

<input type="checkbox" id="abc" value="UDB">UDB
<input type="checkbox" id="abc" value="Prasad">Prasad

$('input#abc').click(function(){
  if($(this).is(':checked'))
  {
    var checkedOne=$(this).val()
    alert(checkedOne);

    // Do some other action
  }
})

This can help if you want that the required action has to be done only when you check the box not at the time you remove the check.

Answer 11

Using the Click event handler for the checkbox property is unreliable, as the checked property can change during the execution of the event handler itself!

Ideally, you'd want to put your code into a change event handler such as it is fired every time the value of the check box is changed (independent of how it's done so).

$('#isAgeSelected').bind('change', function () {

   if ($(this).is(':checked'))
     $("#txtAge").show();
   else
     $("#txtAge").hide();
});

Answer 12

I decided to post an answer on how to do that exact same thing without jQuery. Just because I'm a rebel.

var ageCheckbox = document.getElementById('isAgeSelected');
var ageInput = document.getElementById('txtAge');

// Just because of IE <333
ageCheckbox.onchange = function() {
    // Check if the checkbox is checked, and show/hide the text field.
    ageInput.hidden = this.checked ? false : true;
};

First you get both elements by their ID. Then you assign the checkboxe's onchange event a function that checks whether the checkbox got checked and sets the hidden property of the age text field appropriately. In that example using the ternary operator.

Here is a fiddle for you to test it.

Addendum

If cross-browser compatibility is an issue then I propose to set the CSS display property to none and inline .

elem.style.display = this.checked ? 'inline' : 'none';

Slower but cross-browser compatible.

Answer 13

I believe you could do this:

if ($('#isAgeSelected :checked').size() > 0)
{
    $("#txtAge").show(); 
} else { 
    $("#txtAge").hide();
}

Answer 14

I ran in to the exact same issue. I have an ASP.NET checkbox

<asp:CheckBox ID="chkBox1" CssClass='cssChkBox1' runat="server" />

In the jQuery code I used the following selector to check if the checkbox was checked or not, and it seems to work like a charm.

if ($("'.cssChkBox1 input[type=checkbox]'").is(':checked'))
{ ... } else { ... }

I'm sure you can also use the ID instead of the CssClass,

if ($("'#cssChkBox1 input[type=checkbox]'").is(':checked'))
{ ... } else { ... }

I hope this helps you.

Answer 15

You can try the change event of checkbox to track the :checked state change.

 $("#isAgeSelected").on('change', function() { if ($("#isAgeSelected").is(':checked')) alert("checked"); else { alert("unchecked"); } });

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input type="checkbox" id="isAgeSelected" /> <div id="txtAge" style="display:none"> Age is selected </div>

Answer 16

This code will help you

$('#isAgeSelected').click(function(){
   console.log(this.checked);
   if(this.checked == true) {
        $("#txtAge").show();
    } else {
       $("#txtAge").hide();
   }
});

Answer 17

There are many ways to check if a checkbox is checked or not:

Way to check using jQuery

if (elem.checked)
if ($(elem).prop("checked"))
if ($(elem).is(":checked"))
if ($(elem).attr('checked'))

Check example or also document:

• http://api.jquery.com/attr/

• http://api.jquery.com/prop/

Answer 18

This works for me:

/* isAgeSelected being id for checkbox */

$("#isAgeSelected").click(function(){
  $(this).is(':checked') ? $("#txtAge").show() : $("#txtAge").hide();
});

Answer 19

This is some different method to do the same thing:

 $(document).ready(function (){ $('#isAgeSelected').click(function() { // $("#txtAge").toggle(this.checked); // Using a pure CSS selector if ($(this.checked)) { alert('on check 1'); }; // Using jQuery's is() method if ($(this).is(':checked')) { alert('on checked 2'); }; // // Using jQuery's filter() method if ($(this).filter(':checked')) { alert('on checked 3'); }; }); });

 <script src="http://code.jquery.com/jquery-1.9.1.js"></script> <input type="checkbox" id="isAgeSelected"/> <div id="txtAge" style="display:none">Age is something</div>

Answer 20

Use this:

if ($('input[name="salary_in.Basic"]:checked').length > 0)

The length is greater than zero if the checkbox is checked.

Answer 21

My way of doing this is:

if ( $("#checkbox:checked").length ) {       
    alert("checkbox is checked");
} else {
    alert("checkbox is not checked");
}

Answer 22

$(selector).attr('checked') !== undefined

如果输入被检查，则返回true否则返回false 。

Answer 23

$(document).ready(function() {    
    $('#agecheckbox').click(function() {
        if($(this).is(":checked"))
        {
            $('#agetextbox').show();
        } else {
            $('#agetextbox').hide();
        }
    });
});

Answer 24

You can use:

  if(document.getElementById('isAgeSelected').checked)
    $("#txtAge").show();  
  else
    $("#txtAge").hide();

---

if($("#isAgeSelected").is(':checked'))
  $("#txtAge").show();  
else
  $("#txtAge").hide();

Both of them should work.

Answer 25

1) If your HTML markup is:

<input type="checkbox"  />

attr used:

$(element).attr("checked"); // Will give you undefined as initial value of checkbox is not set

If prop is used:

$(element).prop("checked"); // Will give you false whether or not initial value is set

2) If your HTML markup is:

 <input type="checkbox"  checked="checked" />// May be like this also  checked="true"

attr used:

$(element).attr("checked") // Will return checked whether it is checked="true"

Prop used:

$(element).prop("checked") // Will return true whether checked="checked"

Answer 26

The top answer didn't do it for me. This did though:

<script type="text/javascript">
    $(document).ready(function(){

        $("#li_13").click(function(){
            if($("#agree").attr('checked')){
                $("#saveForm").fadeIn();
            }
            else
            {
                $("#saveForm").fadeOut();
            }
        });
    });
</script>

Basically when the element #li_13 is clicked, it checks if the element # agree (which is the checkbox) is checked by using the .attr('checked') function. If it is then fadeIn the #saveForm element, and if not fadeOut the saveForm element.

Answer 27

This example is for button.

Try the following:

<input type="button" class="check" id="checkall" value="Check All" />  &nbsp; <input type="button" id="remove" value="Delete" /> <br/>

<input type="checkbox" class="cb-element"  value="1" /> Checkbox  1 <br/>
<input type="checkbox" class="cb-element"  value="2" /> Checkbox  2 <br/>
<input type="checkbox" class="cb-element"  value="3" /> Checkbox  3 <br/>


$('#remove').attr('disabled', 'disabled'); 

$(document).ready(function() {  

    $('.cb-element').click(function() {

        if($(this).prop('checked'))
        {
            $('#remove').attr('disabled', false);
        }
        else
        {
            $('#remove').attr('disabled', true);
        }
    });   

    $('.check:button').click(function()
{
    var checked = !$(this).data('checked');
    $('input:checkbox').prop('checked', checked);
    $(this).data('checked', checked);

    if(checked == true)
    {
        $(this).val('Uncheck All');
         $('#remove').attr('disabled', false);
    }

    else if(checked == false)
    {
        $(this).val('Check All');
        $('#remove').attr('disabled', true);
    }
});
});

Answer 28

To act on a checkbox being checked or unchecked on click.

 $('#customCheck1').click(function() { if (this.checked) { console.log('checked'); } else { console.log('un-checked'); } });

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <input type="checkbox" id="customCheck1">

EDIT: Not a nice programming expression if (boolean == true) though .checked property might return other type variables as well..

It is better to use .prop("checked") instead. It returns true and false only.

Answer 29

I am using this:

 <input type="checkbox" id="isAgeSelected" value="1" /> <br/>
 <input type="textbox" id="txtAge" />

 $("#isAgeSelected").is(':checked') ? $("#txtAge").show() : $("#txtAge").hide();

Answer 30

Though you have proposed a JavaScript solution for your problem (displaying a textbox when a checkbox is checked ), this problem could be solved just by css . With this approach, your form works for users who have disabled JavaScript.

Assuming that you have the following HTML:

<label for="show_textbox">Show Textbox</label>
<input id="show_textbox" type="checkbox" />
<input type="text" />

You can use the following CSS to achieve the desired functionality:

 #show_textbox:not(:checked) + input[type=text] {display:none;}

For other scenarios, you may think of appropriate CSS selectors.

Here is a Fiddle to demonstrate this approach .

Answer 31

Toggle: 0/1 or else

<input type="checkbox" id="nolunch" />
<input id="checklunch />"

    $('#nolunch').change(function () {
    if ($(this).is(':checked')) {
        $('#checklunch').val('1');
    };
    if ($(this).is(':checked') == false) {
        $('#checklunch').val('0');
    };
});

Answer 32

Please try below code to check checkbox is checked or not

$(document).ready(function(){

    $("#isAgeSelected").on('change',function(){

    if($("#isAgeSelected").is(':checked'))
        $("#txtAge").show();  // checked
    else{
        $("#txtAge").hide();  // unchecked
    }

   });

});

Answer 33

I'm sure it's not some revelation, but I didn't see it all in one example:

Selector for all checked checkboxes(on the page):

$('input[type=checkbox]:checked')

Answer 34

I verified in Firefox 9.0.1 that the following works for catching the state of a checkbox post change:

$("#mycheckbox").change(function() {
    var value = $(this).prop("checked") ? 'true' : 'false';                     
    alert(value);
});

Answer 35

I think it will be the simple one

$('#isAgeSelected').change(function() {
    if($(this).is(":checked")) {
        $('#txtAge').show();
    }
else{
        $('#txtAge').hide();
    }                                          
});

Answer 36

Include jQuery from the local file system. I used Google's CDN , and there are also many CDNs to choose from.

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>

The code will execute as soon as a checkbox inside mycheck class is clicked. If the current clicked checkbox is checked then it will disable all others and enable the current one. If the current one is unchecked, it will again enable all checkboxes for rechecking.

<script type="text/javascript">
    $(document).ready(function() {

        var checkbox_selector = '.mycheck input[type=checkbox]';

        $(checkbox_selector).click(function() {
            if ($($(this)).is(':checked')) {

                // Disable all checkboxes
                $(checkbox_selector).attr('disabled', 'disabled');

                // Enable current one
                $($(this)).removeAttr('disabled');
            }
            else {
                // If unchecked open all checkbox
                $(checkbox_selector).removeAttr('disabled');
            }
        });
    });
</script>

Simple form to test

<form method="post" action="">
    <div class="mycheck">
        <input type="checkbox" value="1" /> Television
        <input type="checkbox" value="2" /> Computer
        <input type="checkbox" value="3" /> Laptop
        <input type="checkbox" value="4" /> Camera
        <input type="checkbox" value="5" /> Music Systems
    </div>
</form>

Output screen:

Answer 37

if($("#checkkBoxId").is(':checked')){
  alert("Checked=true");
}

or

if($("#checkkBoxId").attr('checked') == true){
  alert("checked=true");
}

Answer 38

The checked attribute of an input type="checkbox" is mapped with the defaultChecked property, not with the checked property.

So when doing something in a page when a checkbox is checked on uncheked, use the prop() method instead. It fetches the property value and changes as the state of the checkbox changes.

Using attr( ) or getAttribute (in pure JavaScript) in these cases are not the proper way of doing things.

if elem is the concerned checkbox then do something like this to fetch the value:

elem.checked

or

$(elem).prop('checked')

Answer 39

Automated

$(document).ready(function()
{
    $('#isAgeSelected').change(function()
    {
        alert( 'value =' + $('#chkSelect').attr('checked') );
    });
});

HTML

<b> <input type="isAgeSelected" id="chkSelect" /> Age Check </b>

<br/><br/>

<input type="button" id="btnCheck" value="check" />

jQuery

$(document).ready(function()
{
    $('#btnCheck').click(function()
    {
        var isChecked = $('#isAgeSelected').attr('checked');

        if (isChecked == 'checked')
            alert('check-box is checked');
        else
            alert('check-box is not checked');
    })
});

Ajax

function check()
{
    if (isAgeSelected())
        alert('check-box is checked');
    else
        alert('check-box is not checked');
}

function isAgeSelected()
{
    return ($get("isAgeSelected").checked == true);
}

Answer 40

This is the minimal amount of code I think I needed to do something like this effectively. I found this method to be useful; it returns an array of the check boxes that are checked and then you can use their value (this solution uses jQuery):

// This is how you get them
var output = "";
var checkedBoxes = $("DivCheckBoxesAreIn").children("input:checked");
if(checkedBoxes.length <= 0) {
    alert('Please select check boxes');
    return false;
};

// And this is how you use them:
checkedBoxes.each(function() {
    output +=  this.value + ", ";
};

Printing "output" will give you a comma-separated list of your values.

Answer 41

 $(document).on("click","#isAgeSelected",function(){ if($(this).prop("checked") == true){ $("#txtAge").show(); } else if($(this).prop("checked") == false){ $("#txtAge").hide(); } });

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input type="checkbox" id="isAgeSelected"/> <div id="txtAge" style="display:none"> <input type="text" name="age" placeholder="Please enter age" /> </div>

Answer 42

I was having the same problem and none of the posted solutions seemed to work and then I found out that it's because ASP.NET renders the CheckBox control as a SPAN with INPUT inside, so the CheckBox ID is actually an ID of a SPAN, not an INPUT, so you should use:

$('#isAgeSelected input')

rather than

$('#isAgeSelected')

and then all methods listed above should work.

Answer 43

Simply use it like below

 $('#isAgeSelected').change(function() {
     if ($(this).is(":checked")) { // or if($("#isAgeSelected").attr('checked') == true){
         $('#txtAge').show();
     } else {
         $('#txtAge').hide();
     }
 });

Answer 44

Using pure JavaScript :

let checkbox = document.getElementById('checkboxID');

if(checkbox.checked) {
  alert('is checked');
} else {
  alert('not checked yet');
}

Answer 45

Here's an example that includes initialising the show/hide to match the state of the checkbox when the page loads ; taking account of the fact that firefox remembers the state of checkboxes when you refresh the page, but won't remember the state of the shown/hidden elements.

$(function() {
    // initialise visibility when page is loaded
    $('tr.invoiceItemRow').toggle($('#showInvoiceItems').attr('checked'));
    // attach click handler to checkbox
    $('#showInvoiceItems').click(function(){ $('tr.invoiceItemRow').toggle(this.checked);})
});

(with help from other answers on this question)

Answer 46

This was my workaround:

$('#vcGoButton').click(function () {
    var buttonStatus = $('#vcChangeLocation').prop('checked');
    console.log("Status is " + buttonStatus);
    if (buttonStatus) {
        var address = $('#vcNewLocation').val();
        var cabNumber = $('#vcVehicleNumber').val();
        $.get('postCabLocation.php',
              {address: address, cabNumber: cabNumber},
              function(data) {
                  console.log("Changed vehicle " + cabNumber + " location to " + address );
              });
    }
    else {
        console.log("VC go button clicked, but no location action");
    }
});

Answer 47

Use:

$(this).toggle($("input:checkbox", $(this))[0].checked);

When you are selecting out of context, remember you need the [0] to access the checkbox.

Answer 48

Setter:

$("#chkmyElement")[0].checked = true;

Getter:

if($("#chkmyElement")[0].checked) {
   alert("enabled");
} else {
   alert("disabled");
}

Answer 49

I would actually prefere the change event.

$('#isAgeSelected').change(function() {
    $("#txtAge").toggle(this.checked);
});

Demo Fiddle

Answer 50

A selector returns multiple objects, and it must take the first item in the array:

// Collection
var chckremember = $("#chckremember");


// Result boolen
var ischecked=chckremember[0].checked;

Answer 51

Try this,

$('#isAgeSelected').click(function() {
    if(this.checked){
        $("#txtAge").show();
    } else{
        $("#txtAge").hide();
    } 
});

Answer 52

I'm using jQuery 1.11.1 and I had troubles with setting and reading checkbox value as well.

I finally solved it by these two functions:

function setCheckboxValue(checkBoxId, checked) {
    if (checkBoxId && (checked === true || checked === false)) {
        var elem = $('#' + checkBoxId);
        if (checked === true) {
            elem.attr('checked', 'checked');
        } else {
            elem.removeAttr('checked');
        }
    }
}

function isChecked(checkBoxId) {
    return $('#' + checkBoxId).attr('checked') != null;
}

It might looks a little bit dirty but it solves all the wired issue I had among different types of browsers.

Answer 53

You Can Try This code:

$('#isAgeSelected').click(function(){
   console.log(this.checked);
   if(this.checked == true) {
        $("#txtAge").show();
    } else {
       $("#txtAge").hide();
   }
});

Answer 54

if( undefined == $('#isAgeSelected').attr('checked') ) {
    $("#txtAge").hide();
} else {
    $("#txtAge").show();
}

Answer 55

What about this solution?

$("#txtAge")[
    $("#isAgeSelected").is(':checked') ?
    'show' :
    'hide'
]();

Answer 56

I need to check the checked property of a checkbox and perform an action based on the checked property using jQuery.

EX -

1) Run On load to get checkbox value if the age checkbox is checked, then I need to show a text box to enter age, else hide the text box.

2) if the age checkbox is checked, then I need to show a text box to enter age, else hide the text box using click event of checkbox.

so code not returns false by default:

Try the following:

<html>
        <head>
            <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
        </head>
        <body>
            <h1>Jquery Demo</h1>
            <input type="checkbox" name="isAge" checked id="isAge"> isAge <br/>
            <div id="Age" style="display:none">
              <label>Enter your age</label>
              <input type="number" name="age">
            </div>
            <script type="text/javascript">
            if(document.getElementById('isAge').checked) {
                $('#Age').show();
            } else {
                $('#Age').hide();
            }   
            $('#isAge').click(function() {
                if(document.getElementById('isAge').checked) {
                    $('#Age').show();
                } else {
                    $('#Age').hide();
                }
            }); 
            </script>
        </body>
    </html>

Here is a modified version: https://jsfiddle.net/sedhal/0hygLtrz/7/

Answer 57

Hi you can use plain Javascript , like so:

 document.getElementById('checkboxOption').addEventListener('click', event => console.log(event.target.checked) );

 <label><input type="checkbox" id="checkboxOption">Check Option</label>

Answer 58

In case you need to know if a checkbox is checked in pure javascript you should use this code.

let checkbox =document.getElementById('myCheckboxId');
if(checkbox.checked) {
    alert("element is checked");
} else {
    alert("element is  ot checked");
}

Answer 59

In pure js checkbox state is easier to read

isAgeSelected.checked

 function check() { txtAge.style.display= isAgeSelected.checked? 'block':'none'; }

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> Age <input type="checkbox" id="isAgeSelected"/> <button onclick="check()">Check</button> <div id="txtAge" style="display:none"> Age is selected </div>

Answer 60

if( undefined == $('#isAgeSelected').attr('checked') ) {
    $("#txtAge").hide();
} else {
    $("#txtAge").show();
}

Answer 61

For older versions of jQuery, I had to use following,

$('#change_plan').live('click', function() {
     var checked = $('#change_plan').attr('checked');
     if(checked) {
          //Code       
     }
     else {
          //Code       
     }
});

Answer 62

$(document).on('change', '#isAgeSelected', function() {

    if($(this).is(":checked")){

       $('#txtAge').hide();
    }
    else
    {
        $('#txtAge').hide();
    }
});

Answer 63

In case if you need to use CSS class as jQuery selector you can do following:

$(document).ready(function () {
        $('.myOptionCheckbox').change(function () {            
            if ($(this).prop('checked') == true) {
                console.log("checked");           
            }
            else {
                console.log("unchecked");                
            }
        });
    });

It works fine for checkboxes and radioboxes as well.

Answer 64

This function is alternative and stable:

$('#isAgeSelected').context.checked
(return True/False)

Example:

if($('#isAgeSelected').context.checked){ //if Checkbox is checked then bla bla..
    /*.....*/
}else{
    /*.....*/
}

Answer 65

$('#chk').change(function() { 
    (this.checked)? alert('true') : alert('false');
});



($('#chk')[0].checked)? alert('true') : alert('false');

Answer 66

if($('#isAgeSelected').prop('checked')) {
    // do your action 
}

Answer 67

You could try the followings in both ways:

var getVal=$('#isAgeSelected').is(":checked"); // jQuery

var getVal=document.getElementById("isAgeSelected").checked //JavaScript

if (getVal==true) {
 $("#txtAge").show();  // checked
} else {
 $("#txtAge").hide();  // unchecked
}

Answer 68

$("#isAgeSelected").prop('checked', true);