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How to implement nationality drop-down box in jquery

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Release： 2023-04-17 15:21:07

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JQuery is a popular JavaScript library that allows web developers to develop various web applications faster and easier. The drop-down box is a common form element that can be used to display options in a list. In this article, we will introduce how to use JQuery to implement a nationality drop-down box.

Step 1: Create an HTML page

First, we need to create an HTML page to contain our drop-down box. On this page we need to add a select element and add our nationality option to it.

<!DOCTYPE html>
<html>
<head>
  <title>JQuery国籍选择下拉框</title>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
</head>
<body>
  <label for="country">选择你的国家:</label>
  <select id="country">
    <option value="">请选择</option>
    <option value="China">中国</option>
    <option value="United States">美国</option>
    <option value="United Kingdom">英国</option>
    <option value="Japan">日本</option>
  </select>
</body>
</html>

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Step 2: Handle the change event

In this step, we will use JQuery to handle the change event of the select element. In this event we will get the value of the selected nationality and execute any code we wish to execute after selecting the nationality.

We first need to select our select element and add a change event listener to it. Once the value of the select element changes, the corresponding code will be executed.

The following is the code we added.

$(document).ready(function() {
  $('#country').change(function() {
    var selected = $(this).val();
    console.log('您选择的国家是：' + selected);
    // 在这里添加任何其他代码
  });
});

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We first use the $(document).ready() function to ensure that the page has been loaded. We then select our select element (here the element with the id "country") and add an event listener to it using the change() function.

In the event listener, we use $(this).val() to get the value of the selected nationality. $(this) is a pointer to our select element, and the .val() function is used to get its value. We also use the console.log() function to print the value of the selected nationality.

Step 3: Complete the Nationality Dropdown Box

In this step, we will add the required code to complete our Nationality Dropdown Box. We will use JQuery to dynamically add our nationality options to the dropdown box.

Here is our complete code.

<!DOCTYPE html>
<html>
<head>
  <title>JQuery国籍选择下拉框</title>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
  <script>
    $(document).ready(function() {

      // 所有国家的数组
      var countries = ['China', 'United States', 'United Kingdom', 'Japan'];

      // 循环遍历国家数组创建选项
      $.each(countries, function(index, value) {
        $('#country').append($('<option>').text(value).attr('value', value));
      });

      // 处理change事件
      $('#country').change(function() {
        var selected = $(this).val();
        console.log('您选择的国家是：' + selected);
        // 在这里添加任何其他代码
      });

    });
  </script>
</head>
<body>
  <label for="country">选择你的国家:</label>
  <select id="country">
    <option value="">请选择</option>
  </select>
</body>
</html>

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In this example, we first create a string array containing all countries. We then use JQuery's $.each function to iterate through this array and create a new options element to add to our dropdown box.

We use the $('#country').append() function to add new option elements. Within this function, we use $('

Finally, we bind all the above code to the $(document).ready() function to ensure that the document has been loaded and the JS code can access the DOM elements.

Summary

This article introduces how to use JQuery to implement a nationality drop-down box. We first created a basic HTML page and added a select element to it. We then complete our drop-down box by dynamically adding nationality options and handling the select element's change event. Using JQuery, we can easily create our own drop-down box and add options dynamically.

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