The difference and application of calculated properties and listening properties in Vue

Vue is a front-end framework. Its flexibility and ease of use make it the first choice for more and more developers in the front-end development process. In Vue, computed properties and listening properties are two very important properties. They are widely used in the data-driven development model. This article will introduce the differences and applications of these two properties.

1. Computed properties

Computed properties are properties that depend on one or more data values ​​and obtain new values ​​through calculation. In Vue's calculated properties, developers only need to define a function and return the calculated result in the function.

For example, in the Vue template, we often need to add two data and display the result. We can define a calculated property like this:

computed: {
  total() {
    return this.num1 + this.num2;
  }
}

In the above example code, computed is Vue One of the attributes of the instance represents a calculated property, and total is our custom calculated property name, where this.num1 and this.num2 are two dependencies.

When num1 or num2 changes, Vue will automatically recalculate the value of total and display the result.

In addition, when the same calculation needs to be used in multiple templates, it can also be encapsulated into a reusable calculated attribute.

2. Listening attributes

Listening attributes are attributes that perform some logic when a specified data changes. In Vue, developers can monitor data changes through the watch attribute.

For example, we need to monitor whether a certain data changes and trigger certain functions when it changes. We can use the listening attribute like this:

watch: {
  targetData(newVal, oldVal) {
    // do something
  }
}

In the above example code, watch is Vue One of the attributes of the instance represents the listening attribute. targetData is the data we need to monitor. When it changes, the logic code in the function will be executed.

3. Differences and Applications

In Vue, calculated properties and listening properties are both very commonly used and important properties. The difference between them is:

• Computed properties calculate and return new values ​​based on their dependencies, while listening properties perform some logic when the data changes.
• Computed properties are suitable for data that does not change frequently, while listening properties are suitable for scenarios where some operations need to be performed when the data changes.

For the application of these two attributes, they can be used to implement complex business logic, or optimize the performance of the code, etc.

For example, for scenarios that require complex calculations on data, calculated properties can be used to improve the readability and maintainability of the code. In scenarios where subsequent operations need to be performed based on changes in data, listening attributes can be used to meet the requirements.

Summary

Computed properties and listening properties are very commonly used properties in Vue. They can not only implement complex business logic, but also improve the readability and maintainability of the code. When using it, you need to choose which attribute to use according to the specific scenario to achieve better results.

The above is the detailed content of The difference and application of calculated properties and listening properties in Vue. For more information, please follow other related articles on the PHP Chinese website!