v-model function in Vue3: application of two-way data binding

Vue is one of the most popular front-end frameworks at present. It has a typical MVC (Model-View-Controller) architecture to facilitate the integration of data and views. In Vue 3, the v-model function plays an important role as the core of two-way data binding. This article will discuss common applications of this function in Vue applications.

1. Principle
   First we need to understand the principle of v-model function. In layman's terms, the v-model function is a function that binds data from the model to the view. When the value in the view changes, v-model will propagate the change back to the corresponding model. This "interoperability" mechanism is the basis for Vue to implement two-way data binding.
2. Example
   Next, the usage of the v-model function will be explained with a simple form example. The following code implements a simple Vue model:

  
{{message}}
 

var app = new Vue({ el: '#app', data: { message: '' } })

This model provides a single-line text box and a paragraph component. When the text box is entered, the paragraph component instantly displays the entered value. This implementation is convenient and intuitive, and does not need to be used similar to the template syntax in Vue1 and Vue2. It can be seen that the v-model function is simpler and easier to use in Vue 3.

3. Modifiers
   In addition to the above application methods, the v-model function also provides some modifiers to optimize the actual application experience. For example, when entering a password, the user needs to confirm the password before submitting.

   Submit 

In this example, the v-model function modifier trim removes possible irrelevant character input by the user. You can also use the v-model function modifier to check whether the user's input complies with the rules, such as limiting the number of input characters, limiting the types of input characters, etc.

4. Custom component
   How to use v-model function in custom Vue component? Vue 3 provides a way to customize the v-model function. For example, the following code demonstrates a custom input box component:

Vue.component('custom-input', { props: ['modelValue'], template: `  ` })

In this custom component, match the standard of the v-model function Usage, prop passes in the modelValue attribute, and the input box will automatically update the value of modelValue.

5. Summary
   Through the above examples, we can see that the v-model function is so common in Vue applications: it is convenient, practical, intuitive and natural, and can be very flexible to adapt to different business scenarios. By mastering the usage and modifiers of the v-model function, the efficiency and convenience of Vue applications can be improved.

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