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How to use Vue to implement multi-level linkage effects

WBOYOriginal: 2023-09-19 08:48:171521browse

Overview:
In modern web development, multi-level linkage (also called cascade selection) is a A very common interaction effect. It allows the user to dynamically update subordinate options by selecting a superior option. In this article, we will explore how to use the Vue framework to implement a simple multi-level linkage effect and provide specific code examples.

Step 1: Create a Vue application
First, we need to create a basic Vue application. We can complete this step by importing the Vue.js file and adding a Vue instance in the HTML file.

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>多级联动特效</title>
  <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
  <div id="app">
    <select v-model="selectedProvince" @change="updateCities">
      <option v-for="province in provinces" :value="province">{{ province }}</option>
    </select>
    <select v-model="selectedCity">
      <option v-for="city in cities" :value="city">{{ city }}</option>
    </select>
  </div>

  <script>
    new Vue({
      el: '#app',
      data: {
        selectedProvince: '',
        selectedCity: '',
        provinces: ['北京', '上海', '广东'],
        cities: []
      },
      methods: {
        updateCities() {
          if (this.selectedProvince === '北京') {
            this.cities = ['北京'];
          } else if (this.selectedProvince === '上海') {
            this.cities = ['上海'];
          } else if (this.selectedProvince === '广东') {
            this.cities = ['广州', '深圳', '珠海'];
          } else {
            this.cities = [];
          }
          this.selectedCity = '';
        }
      }
    })
  </script>
</body>
</html>

In the above code, we create a Vue instance and define selectedProvince, selectedCity, provinces and citiesVariables. The selectedProvince and selectedCity variables are used to store the currently selected province and city. The provinces array contains all optional provinces, and the cities array stores the list of cities under the currently selected province.

Step 2: Implement cascade update
Next, we need to implement the function that when the user selects a province, the city options will be dynamically updated. In order to achieve this goal, we achieve this by listening to the change event of the select element and calling the updateCities method.

In the updateCities method, we first update the city list based on the selected province. According to the example, we used a simple if-else statement to implement, but in actual applications it may be necessary to obtain data from the backend API. When the province changes, we update the city list based on the selected province and reset the selected city to empty.

Finally, make sure to mount the Vue instance to the <div id="app"> element in the HTML template so that Vue can manage the application's state and update the view. <p> Code explanation: </p> <ul> <li> Two-way binding can be achieved through the <code>v-model instruction, binding selectedProvince to the firstselect element, selectedCity is bound to the second select element. The

v-for instruction is used to traverse the provinces and cities arrays to generate the corresponding options. The

@change directive is used to monitor the change event of the select element and call the updateCities method when the province changes. .

Summary:
In this article, we learned how to use the Vue framework to implement a simple multi-level linkage special effect. By listening to the change events of the select element and dynamically updating the city options based on the selected province, we can create a smooth and user-friendly multi-level linkage effect. I hope this example can help you better understand and use the Vue framework.

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