Vue.js Filters

/ #Vue.js


Filters are justed to apply formatting and transformations to values used in a template interpolation. You include filters in you components and you can use them on all dynamic data. The underlying data will not be change, just the way they are presented on the screen.

A quick greeting example

<template>
    <p>Hello {{ firstName }}!</p>
</template>

<script>
    export default {
        data() {
            return {
                firstName: ''
            }
        }
    }
</script>

If you run this code, the output will look like this:

Hello !

And that does not look good. Let create a simple filter so that if "firstName" is empty, we print "World" instead. Let's change the code so it looks like this:

<template>
    <p>Hello {{ firstName | fallback }}!</p>
</template>

<script>
    export default {
        data() {
            return {
                firstName: ''
            }
        },
        filters: {
            fallback: function(firstName) {
                return firstName ? firstName : 'World'
            }
        }
    }
</script>

If you run this command, the output will look like this:

Hello World!

As you can see, applying filters are really easy. The filters objects can contain a lot of different filters. They accept one value (the value before the pipe/|) and they can return the value with the applied filter. Since Vue.js is so awesome, you can also access the components data and methods too!

A better example

In this example I'm going to show you how to truncate text using a Vue.js filter.

<template>
    <p>{{ lorem | truncate }}</p>
</template>

<script>
    export default {
        data() {
            return {
                lorem: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam nibh mauris, euismod sed pulvinar id, aliquam eu turpis. Donec in rutrum mauris.'
            }
        },
        filters: {
            truncate: function(text) {
                return text.substring(0, 10)
            }
        }
    }
</script>

If you run the code in this example, you will see something like this:

Lorem ipsu

But what if you want to have a dynamic limit? Change the example above to make it look like this:

<template>
    <p>{{ lorem | truncate(15) }}</p>
</template>

<script>
    export default {
        data() {
            return {
                lorem: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam nibh mauris, euismod sed pulvinar id, aliquam eu turpis. Donec in rutrum mauris.'
            }
        },
        filters: {
            truncate: function(text, limit) {
                return text.substring(0, limit)
            }
        }
    }
</script>

If you run the code in this example, you will see something like this:

Lorem ipsum dol

What else can I use Vue.js filters for?

There are several things you can use filters for like capitalizing, lowercasing an e-mail address, adding prefixed to prices and so much more.

Other Vue.js tutorials

-A short introduction to Vue.js watchers
-Introduction to Vue.js props


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