jquery select not checked

jQuery is one of the most popular tools in JS. It provides many simple and easy-to-use methods to facilitate us to process DOM elements in web pages. When processing forms, we often need to select the selected radio and checkbox elements in the form elements. However, we occasionally encounter such a situation. How to select elements that do not have a checked attribute in the form?

First, we need to understand the status of the form elements. For a radio button and check box, they have a checked state. This status can be true or false. If it is checked, it is true, otherwise it is false. In the DOM, we can access them through the checked attribute.

For radio buttons, only one will be selected. The following HTML code is a form element composed of two radio buttons:

<input type="radio" name="gender" value="male" checked>男
<input type="radio" name="gender" value="female">女

By accessing the checked attribute, we can find the selected radio button element:

var selectedRadio = $('input[name="gender"]:checked');

For check boxes, they may There are multiple selections. The following HTML code is a form element composed of two check boxes:

<input type="checkbox" name="interest" value="music" checked>音乐
<input type="checkbox" name="interest" value="sports">运动

We can find the selected check box element by accessing the checked attribute:

var selectedCheckbox = $('input[name="interest"]:checked');

However, if there is no checked attribute, what should we do?

Method 1: Use the :has() pseudo-class of the selector

We can use the :has() pseudo-class of the jQuery selector, which can select parent elements with specific child elements. For radio buttons and checkboxes that do not have a checked attribute, we can use the :not() pseudo-class to filter them, and then use the :has() pseudo-class to select their parent elements.

For example, we have the following HTML code:

<input type="radio" name="gender" value="male">男
<input type="radio" name="gender" value="female">女

We can use the following code to select the parent element of an unchecked radio button:

var unselectedRadioParent = $('input[name="gender"]:not(:checked)').parent();

Similarly, for the check For box elements, we can use a similar method:

var unselectedCheckboxParent = $('input[name="interest"]:not(:checked)').parent();

It is worth noting that the :not() pseudo-class selector is more performance-intensive. Therefore, it is recommended to use the second method if you have a large number of radio button or checkbox elements in your form.

Method 2: Use the filter() method

The filter() method is used to filter the collection of elements that match a given selector or function. We can use the filter() method to filter out all selected radio button or checkbox elements and then use the not() method to filter out other elements.

For example, for the following radio button group, we can use the following code to select the unchecked radio button elements:

var unselectedRadio = $('input[name="gender"]').not(':checked');

Similarly, for the following checkbox group, we can use The following code selects unchecked checkbox elements:

var unselectedCheckbox = $('input[name="interest"]').not(':checked');

Summary

In form elements, we often need to select selected radio buttons and checkbox elements. If there is no checked attribute in the form element, we can use the :has() pseudo-class or filter() method of the selector to select unchecked radio button and checkbox elements. These methods provide us with more flexible choices when processing forms, allowing us to easily handle forms in various situations.

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