jquery 如何使复选框始终处于选中状态

Question

How can I make a checkbox always be checked, with Jquery 1.4.2?

This is my html output from the struts application:

<input type="checkbox" name="helloThere" value="on">

I tried:

$(document).ready(function() {
    $('#helloThere').attr('checked', 'checked');
});

JSFIDDLE

http://jsfiddle.net/96p4zg9w/ this shows the current code, I would need the checkbox to load checked.

The props property is not available in JQUERY 1.4.2

Answer 1

your jquery selector is wrong.

You are trying select an element with 'helloThere' id, but your input has not an id attribute. You can add this attribute to your input field or change jquery selector.

Try one of this tow solutions:

<input type="checkbox" name="helloThere" id="helloThere" value="on">

or

$(document).ready(function() {
    $("input[name='helloThere']").attr('checked', 'checked');
});

Answer 2

You need to put your JavaScript inside $(document).ready() . This ensures all of the content you might want to touch has been loaded before you try to change it.

In your scenario then, you would need:

$(document).ready(function() {
    $('#helloThere').attr('checked', 'checked');
});

Edit : Your checkbox doesn't have an ID. You need to add an ID of "helloThere" for $('#helloThere') to pick it up. Your fiddle also needs to have jQuery loaded using the menu on the left. Here's a working version: http://jsfiddle.net/96p4zg9w/1/

Answer 3

Check this jsfiddle for a working example of how you can do it using javascript. If you want to use versions of jQuery below 1.5, you need to do it this way:

$("#checkbox").attr("checked", true);

or

$("#checkbox").attr("checked", "checked");

If you want to select element using the name instead of id, use:

input[name='helloThere']

Hope it useful!

Answer 4

It can be done in three ways. You can use checked in input that will always stay checked.

<input id="myId" type="checkbox" name="name" checked>

Using prop and assume input id is myId

 $(document).ready(function() {
     $(#myId).prop('checked', true);
 });

Before jQuery 1.6 using attr

 $(document).ready(function() {
     $(#ID).attr('checked','checked');
 });

Answer 5

 <lable>this will always be checked, even you try to uncheck</lable>: <input type="checkbox" checked onclick="return false;">