jquery dynamically obtains the value of whether the checkbox is selected

In web development, it is often necessary to obtain the selected status of a checkbox. Using jQuery can simplify this process.

jQuery is a fast, small, feature-rich JavaScript library. It provides a convenient and simplified JavaScript API for HTML document traversal and manipulation, event handling, animation, Ajax and other operations. The design philosophy of jQuery is "Write less, do more". It can help developers use simple code to implement complex functions. In front-end development, jQuery has become an essential tool.

When using jQuery to obtain the selected state of a check box, you need to use jQuery's selector to select the element to be operated, and then obtain the selected state through the methods provided by jQuery.

Here is a simple example:

<input type="checkbox" id="checkbox1" name="option1" value="1">选项1
<input type="checkbox" id="checkbox2" name="option2" value="2">选项2
<input type="checkbox" id="checkbox3" name="option3" value="3">选项3
<button id="submitBtn">提交</button>

<script>
$(function() {
  $('#submitBtn').on('click', function() {
    var checkedVals = $('input[name="option"]:checked').map(function() {
      return this.value;
    }).get();
    console.log('选中的值为：' + checkedVals.join(', '));
  });
});
</script>

In the above example, there are three checkboxes and one button. When the button is clicked, the code gets the value of the selected checkbox and prints it to the console.

The methods involved in the code are:

• $('#submitBtn').on('click', function() {...}): Function executed when the button is clicked.
• $('input[name="option"]:checked'): Select all check boxes whose name is "option" and are selected.
• .map(function() {...}): Map the value of the selected check box through the function return value.
• .get(): Convert the mapped value to an array type.

Through these methods, you can easily get the checked status of the check box.

Of course, there are other ways to get the checked status of the check box. For example, you can use the JavaScript native method:

var checkboxes = document.querySelectorAll('input[name="option"]');
var checkedVals = [];

for (var i = 0; i < checkboxes.length; i++) {
  if (checkboxes[i].checked) {
    checkedVals.push(checkboxes[i].value);
  }
}

console.log('选中的值为：' + checkedVals.join(', '));

Using this method, you need to manually traverse all check boxes, determine whether they are selected, and save the selected values ​​​​in an array.

In general, jQuery provides a simple and convenient way to get the selected status of the check box. At the same time, you can also easily implement other DOM operations using jQuery, such as adding, deleting, modifying, and checking.

In addition, it should be noted that when using jQuery, you need to pay attention to the performance of the code. If there are too many elements on the page, it may affect the page's loading speed and user experience. Therefore, the code should be streamlined as much as possible to avoid repeated calculations and meaningless operations.

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