Tips for using filters to implement data formatting and data filtering in Vue

Vue.js is a popular JavaScript framework that provides many useful features and tools to help front-end developers develop excellent applications. Among them, filters are a very useful function in Vue.js, which can be used for data formatting and filtering.

In Vue, filters are equivalent to pipelines in templates and can be used to process and transform data. For example, we can use filters to convert a date format from a raw date string to a human-friendly date format, or to format a number into a currency format.

In this article, we will introduce some techniques for using filters in Vue to implement data formatting and data filtering, making your application more elegant and easier to maintain.

1. Create filter

In Vue, we can create a filter through the Vue.filter method. This method requires two parameters: the name of the filter and the specific processing function. For example:

Vue.filter('capitalize', function (value) {
  if (!value) return ''
  value = value.toString()
  return value.charAt(0).toUpperCase() + value.slice(1)
})

The above code creates a filter named capitalize, which converts the first character of the string to uppercase letters. This filter can be used in templates:

<div>{{ message | capitalize }}</div>

2. Processing arrays

When we have an array that needs to be processed, we can use the filter method to filter or transform the data in the array . For example:

Vue.filter('excludeSpaces', function (arr) {
  return arr.filter(function (item) {
    return item.indexOf(' ') < 0
  })
})

The above code creates a filter named excludeSpaces, which will filter elements in the array that contain spaces. This filter can be used in templates:

<div>{{ ['Hello World', 'Vue Developer', 'Goodbye'] | excludeSpaces }}</div>

The output result is: ["Vue Developer", "Goodbye"].

3. Processing dates

In Vue, we can use the moment.js library to process dates, or use custom filters to format date.

The following is an example of using filters to format a date:

Vue.filter('formatDate', function (value) {
  if (value) {
    return moment(String(value)).format('MM/DD/YYYY hh:mm')
  }
})

The above code creates a filter named formatDate, which formats the date as The format is MM/DD/YYYY hh:mm. The filter can be used in templates:

<div>{{ date | formatDate }}</div>

4. Processing numbers

In Vue, we can use filters to format numbers. Here is an example of converting a number to currency format:

Vue.filter('formatPrice', function (value) {
  if (!value) return ''
  let val = (value / 1).toFixed(2).replace(',', '.')
  return '$' + val.toString().replace(/B(?=(d{3})+(?!d))/g, ',')
})

The above code creates a filter named formatPrice which formats a number into currency format. This filter can be used in templates:

<div>{{ price | formatPrice }}</div>

5. Combined with computed properties

In Vue, we can combine computed properties with filters to further expand the functionality of filters. For example:

Vue.filter('uppercase', function (value) {
  if (!value) return ''
  return value.toString().toUpperCase()
})

Vue.filter('length', function (value) {
  if (!value) return ''
  return value.length
})

new Vue({
  el: '#app',
  data: {
    message: 'hello vue'
  },
  computed: {
    upperMessage () {
      return this.message | uppercase
    },
    messageLength () {
      return this.message | length
    }
  }
})

The above code uses two filters, uppercase and length, to process and convert data in calculated attributes.

Use in the template:

<div>{{ upperMessage }}</div>
<div>{{ message | uppercase | length }}</div>
<div>{{ messageLength }}</div>

The final output of the above code is:

HELLO VUE
9
9

6. Summary

The filters function in Vue It is very powerful and can be used for data formatting and filtering, and can also be combined with calculated properties to further extend the functionality. In actual development, using filters can greatly simplify the complexity of the code and improve the maintainability and readability of the code. If you haven’t used filters when using Vue, you might as well try it!

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