Detailed explanation of Vue.set function and how to dynamically add responsive attributes

Detailed explanation of the Vue.set function and how to dynamically add responsive attributes

Vue.js is a popular JavaScript framework that provides a simple, efficient, and flexible way to build user interfaces. In Vue.js, we can use responsive attributes to implement two-way binding of data, so that data changes can be automatically reflected on the interface. However, sometimes we need to add responsive properties dynamically, then we need to use the Vue.set function.

The Vue.set function is a global function provided by Vue.js, which is used to add a responsive attribute to an existing data object. Its usage is very simple. We only need to pass in a target object, a property name and a value, and the Vue.set function will automatically convert the property into a responsive property. The following is an example:

// 创建一个Vue实例
var vm = new Vue({
  data: {
    obj: {
      name: '张三',
      age: 18
    }
  }
})

// 动态添加一个响应式属性
Vue.set(vm.obj, 'gender', '男')

// 输出结果
console.log(vm.obj.gender) // 男

In this example, we create a Vue instance vm and define an obj object under the data attribute, which contains the 'name' and 'age' attributes. Then, we use the Vue.set function to dynamically add a 'gender' attribute and assign it the value 'male'. Finally, we output the value of vm.obj.gender, and you can see that it outputs 'male', indicating that a responsive attribute was successfully added.

It should be noted that the Vue.set function can only be used for existing data objects. If we try to use the Vue.set function to add responsiveness to a property that does not originally exist, it will not work. This is because Vue.js only performs responsive processing on existing properties when initializing data.

In addition to the Vue.set function, we can also use the Vue.$set method to achieve the same effect. The Vue.$set method is an instance method of Vue.js and can be called directly through the Vue instance. The following is the equivalent code of the above example:

// 创建一个Vue实例
var vm = new Vue({
  data: {
    obj: {
      name: '张三',
      age: 18
    }
  }
})

// 动态添加一个响应式属性
vm.$set(vm.obj, 'gender', '男')

// 输出结果
console.log(vm.obj.gender) // 男

As you can see, the effect of using the Vue.$set method and the Vue.set function is the same, and they can both dynamically add responsive properties.

To summarize, the Vue.set function and Vue.$set method are methods provided by Vue.js for dynamically adding responsive properties. They can easily realize two-way binding of data, so that changes in data can be automatically updated on the interface. When using the Vue.set function or Vue.$set method, please note that it can only act on existing properties. If the attribute to be added does not originally exist, it needs to be defined first when initializing the data.

I hope this article will be helpful to you in learning and using Vue.js!

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