VUE3 basic tutorial: Use Vue.js filters to encapsulate data

Vue.js is a lightweight JavaScript framework with a series of features and functions to improve the efficiency of web application development. Vue3, as the latest version of Vue.js, provides developers with more features and functions, especially for data filtering and sorting. Vue.js can encapsulate and adjust data through filters. This article will introduce in detail how to use Vue.js filters to encapsulate data.

1. What are Vue.js filters?

Vue.js filter is a technology that can be used to format {{expression}} data in Vue templates. A filter is similar to a pipeline system that receives input data, processes it, and finally outputs the processed data to the template. Vue.js filters are very flexible and can easily adapt to most development needs.

2. How to use Vue.js filter?

Vue.js filters can be created through the filter method on the Vue.js instance. Vue.js uses the pipe (|) symbol to represent the filter of data, as shown below:

{{ expression | filter1 | filter 2 | ... }}

The above formula represents, Apply filter1 to the expression data first, then pass the output into filter2 and continue processing until all filters have been applied.

2.1 Simple Vue.js filter example

The following example shows how to use Vue.js's filter to adjust the date format. In the following example, the Date parameter represents a specific date, and dateFormat represents the format string. The Date parameter needs to be a JavaScript Date object, or you can use a date library such as moment.js.

Vue.filter('dateFormat', function (Date, dateFormat) {
  return moment(Date).format(dateFormat);
});

var app = new Vue({
  el: '#app',
  data: {
    myDate: '2017-04-12',
    format: 'MM/DD/YYYY'
  }
})

In HTML code, we can use the dateFormat filter in the following way:

<div id="app">
  <p>Date: {{myDate | dateFormat(format)}}</p>
</div>

In the above code, we apply the filter dateFormat and pass format as a parameter to filter. Therefore, we will get a date in the format 04/12/2017.

2.2 Composite filter example

Multiple Vue.js filters can be used together through "pipes" (|), as shown below:

Vue.filter('reverse', function (value) {
  return value.split('').reverse().join('');
});

Vue.filter('capitalize', function (value) {
  return value.toUpperCase();
});

Vue.filter('reverseAndCapitalize', function (value) {
  return this.reverse(this.capitalize(value));
});

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

In the above In the code, we define three filters: reverse, capitalize and reverseAndCapitalize, where reverseAndCapitalize is a compound filter that combines reverse and capitalize through pipelines. In HTML code, we can use the reverseAndCapitalize filter in the following way:

<div id="app">
  <p>Message: {{ message | reverseAndCapitalize }}</p>
</div>

In the above code, we first apply the capitalize filter and then reverse the filter to convert the output to DLROW OLLEH.

3. Summary

Vue.js filter is a very powerful data processing tool that can format, adjust and sort data through filters. In this article, we introduced the basics of Vue.js filters and provided some use cases to further explain the application of filters. If you want to learn more about Vue.js, you can check out the official documentation of Vue.js for more details about filters and other features.

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