How to Create Filters in Vue.js with Examples

How to Create Filters in Vue.js with Examples

In this artilce, you'll know how to create and use filters in Vue.js and most importantly you can refactor your code and clean it a bit with filters.

Similar to AngularJS, Vue.js has its way of transforming data and applying filters to it, but you must keep in mind that filters don't transform the original data, they only change the output and return a filtered version of it. Filters can be useful in a lot of different situations like keeping your API responses as clean as possible and handling the formatting of your data on your frontend. They can also be efficient in cases where you want to avoid repetition and concatenation by encapsulating all that logic behind reusable code blocks.

I hope this small introduction got you excited to learn more about Filters. How you can create and use them and couple more things you will discover going through the article. HERE WE GO!

Table of Contents

  • Vue.js Default Filters
  • Defining and Using Filters
  • Global Filters
  • Local Filters
  • Additional Arguments
  • Chaining Filters
  • Examples
  • Conclusion
Vue.js Default Filters

Built-in filters can be useful, but they lack the flexibility of pure JavaScript. When a built-in function doesn't suit your needs, you either end up re-implementing something similar (and shipping both in your final code, where the built-in becomes useless, dead code) or have to wait for Vue to update them and release a new version.

With that in mind, be careful reading or watching old tutorials. Here is a full list of the old default filters in case you want to learn more about them: Filters - vue.js.

Spoiler Alert: We will be reproducing few of them in the examples below

Defining and Using Filters

With Vue, you can register your filters in two different ways: Globally and Locally. The former gives you access to your filter across all your components, unlike the latter which only allows you to use your filter inside the component it was defined in.

Filters are simple JavaScript functions, they take the value to be transformed as the first parameter, but you can also pass in as many other arguments as you will need to return the formatted version of that value.

Global Filters

Here is what a Global filter looks like:

// In this example, we will register a global filter
// which will add the dollar sign in front of the price:

// DECLARATION
Vue.filter('toUSD', function (value) {
    return `$${value}`;
});

// USAGE
<div id="app">
  <span>{{ 351.99 | toUSD }}</span>
</div>

PS: The filter definition must always be above the main Vue instance, or you will get a “Failed to resolve filter: toUSD” error.

// DECLARATION
Vue.filter('toUSD', function (value) {
    return `$${value}`;
});

new Vue({
    el: '#app',

     data: {
        price: 351.99
    }
});

// USAGE
<div id="app">
  <span>{{ price | toUSD }}</span>
</div>

See it in action

Local Filters

Local filters are registered to a Vue component scope. The following illustrates how they are created:

// In this example, we are creating a filter 
// That turns the string you give it to upper-case.

// DECLARATION
new Vue({
    el: '#app',

    data: {
        name: 'scotch.io'
    },

    filters: {
       // Filter definitions
        Upper(value) {
            return value.toUpperCase();
        }
    }
});

// USAGE
<div id="app">
  <span>{{ name | Upper }}</span>
</div>

See it in action

As you can see in the example above, Local Filters are stored within the Vue component as functions inside the “filters” property. You can register as many as you want:

...
    filters: {
        Upper(value) {
              return value.toUpperCase();
        },
        Lower(value) {
            return value. toLowerCase();
        },
    }
....
Additional Arguments

As we mentioned in the introduction of this article, Filters can take as many arguments as you need:


// DECLARATION
Vue.filter('readMore', function (text, length, suffix) {
    return text.substring(0, length) + suffix;
});

new Vue({
    el: '#app',

    data: {
        text: 'Lorem ipsum dolor sit amet, consectetur adipisicing elit. Non ab modi repellendus labore facere, fugiat ipsam quae accusantium commodi voluptas nesciunt dolor similique ipsum accusamus earum eligendi suscipit laborum quod.'
    }
});

// USAGE
<div id="app">
  <span>{{ text | readMore(10, '...') }}</span>
</div>

In this example, we created a filter with the name “readMore” which will limit the length of a string to a given number of characters and will also append a suffix of your choice to it. Vue.js passes the value to be filtered as the first param text and length, suffix as the second and third parameter.

See it in action: Edit fiddle - JSFiddle

Chaining Filters

One of my favorite things about Filters is the ability to chain them using the pipe ( | ) symbol and run a single value through a series of transformers. Let’s use the example of price value again; we want to limit it to two numbers after a comma and add the dollar sign to it.

Although we can achieve this using one single filter we might also want to use toUSD filter on its own. Separating and chaining filters, in this case, is the way to go:

Vue.filter('toFixed', function (price, limit) {
    return price.toFixed(limit);
});

Vue.filter('toUSD', function (price) {
    return `$${price}`;
});

new Vue({
    el: '#app',

    data: {
        price: 435.333
    }
});
<div id="app">
  <span>{{ price | toFixed(2) | toUSD }}</span>
</div>

Check it out in action

Examples

If you made it to this part of the article, congratulations! That was everything you needed to know about Vue.js filters, but it is always a good idea to go through few examples:

  • Convert a JavaScript value to a JSON string:
Vue.filter('json', function (value) {
    return JSON.stringify(value);
});

new Vue({
    el: '#app',

    data: {
        user: {
            username: 'johndoe',
            email: '[email protected]',
            countryCode: 'U.K.'
        }
    }
});
<div id="app">
  <span>{{ user | json }}</span>
</div>

Edit fiddle - JSFiddle

  • Extracting a list of property values from an array of objects:
Vue.filter('pluck', function (objects, key) {
    return objects.map(function(object) { 
        return object[key];
    });
});

new Vue({
    el: '#app',

    data: {
        users: [
        {
            "id": 4,
            "first_name": "Eve",
            "last_name": "Holt"
        },
        {
            "id": 5,
            "first_name": "Charles",
            "last_name": "Morris"
        },
        {
            "id": 6,
            "first_name": "Tracey",
            "last_name": "Ramos"
        }
        ]
    }
});
<div id="app">
  <span>{{ users | pluck('last_name') }}</span>
</div>

Edit fiddle - JSFiddle

  • Return the element at the given index:
Vue.filter('at', function (value, index) {
    return value[index];
});

new Vue({
    el: '#app',

    data: {
        videos: ['Zi_XLOBDo_Y', 'sOnqjkJTMaA', 'sOnqjkJTMaA']
    }
});
<div id="app">
  <span>{{ videos | at(1) }}</span>
</div>

Edit fiddle - JSFiddle

  • Return the minimum value in a given list:
Vue.filter('min', function (values) {
    return Math.min(...values);
});

new Vue({
    el: '#app',

    data: {
        ages: [23, 19, 45, 12, 32]
    }
});
<div id="app">
  <span>{{ ages | min }}</span>
</div>

Edit fiddle - JSFiddle

  • Shuffle a list of elements:
Vue.filter('shuffle', function (values) {
    for (var i = values.length - 1; i > 0; i--) {
        var j = Math.floor(Math.random() * (i + 1));
        var temp = values[i];
        values[i] = values[j];
        values[j] = temp;
    }
    return values;
});

new Vue({
    el: '#app',

    data: {
        cards: ['Lahire', 'Judith', 'Lancelot', 'Alexandre']
    }
});
<div id="app">
  <span>{{ cards | shuffle }}</span>
</div>

Edit fiddle - JSFiddle

  • Return the first element of an array:
Vue.filter('first', function (values) {
    if(Array.isArray(values)) {
        return values[0];
    }
    return values;
});

new Vue({
    el: '#app',

    data: {
        consoles: ['PlayStation', 'Nintendo DS', 'Xbox', 'Atari']
    }
});
<div id="app">
  <span>{{ consoles | first }}</span>
</div>

Edit fiddle - JSFiddle

  • Return the last element of an array:
Vue.filter('last', function (values) {
    if(Array.isArray(values)) {
        return values[values.length - 1];
    }
    return values;
});

new Vue({
    el: '#app',

    data: {
        consoles: ['PlayStation', 'Nintendo DS', 'Xbox', 'Atari']
    }
});
<div id="app">
  <span>{{ consoles | last }}</span>
</div>

Edit fiddle - JSFiddle

  • Return a copy of the array without the given elements:
Vue.filter('without', function (values, exclude) {
    return values.filter(function(element) {
        return !exclude.includes(element);
    });
});

new Vue({
    el: '#app',

    data: {
        unpaidInvoices: ['#1001', '#1002', '#1003', '#1004']
    }
});
<div id="app">
  <span>{{ unpaidInvoices | without('#1003') }}</span>
</div>

Edit fiddle - JSFiddle

  • Remove duplicated elements in an array:
Vue.filter('unique', function (values, unique) {
    return values.filter(function(element, index, self) {
        return index == self.indexOf(element);
    });
});

new Vue({
    el: '#app',

    data: {
        recentViewedPosts: [13, 43, 23, 13, 43, 3, 98, 42, 65]
    }
});
<div id="app">
  <span>{{ recentViewedPosts | unique }}</span>
</div>

Edit fiddle - JSFiddle

  • Prepend text to a string:
Vue.filter('prepend', function (string, prepend) {
    return `${string}${prepend}`;
});

new Vue({
    el: '#app',

    data: {
        greeting: 'Hello'
    }
});
<div id="app">
  <span>{{ greeting | prepend(' World!') }}</span>
</div>

Edit fiddle - JSFiddle

  • Repeat a string n times:
Vue.filter('repeat', function (string, times) {
    return string.repeat(times);
});

new Vue({
    el: '#app',

    data: {
        greeting: 'Hello'
    }
});
<div id="app">
  <span>{{ greeting | repeat(3) }}</span>
</div>

Edit fiddle - JSFiddle

If you are interested in these filters and you want to use them in your project GitHub - wy-ei/vue-filter: A collection of Vue.js filter. offers a set of a very useful Vue.js filters including the ones above. Head over there to see how you can install and use them.

Conclusion

I hope you learned something from this post and you now know how to create and use filters and most importantly you can now refactor your code and clean it a bit with filters.

Thanks for reading

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Further reading

Vue JS 2 - The Complete Guide (incl. Vue Router & Vuex)

Nuxt.js - Vue.js on Steroids

Build Web Apps with Vue JS 2 & Firebase

Build a Progressive Web App In VueJs

Build a Basic CRUD App with Vue.js and Node

Best JavaScript Frameworks, Libraries and Tools to Use in 2019

What are the differences between the various JavaScript frameworks? E.g. Vue.js, Angular.js, React.js

What are the differences? Do they each have specific use contexts?

What are the differences? Do they each have specific use contexts?

Ember.js vs Vue.js - Which is JavaScript Framework Works Better for You

Ember.js vs Vue.js - Which is JavaScript Framework Works Better for You

In this article we will discuss full details and comparison of both Ember.js and Vue.js

JavaScript was initially created to work for web applications. But today they have become the favorite of mobile app developers. Most of the developers prefer to work with frameworks based on JavaScript. It simplifies coding. You can use JavaScript with almost any framework.

The use of a particular framework will decide how easy and fast it is to create the app. So, you must choose the best one suited for the app that you are planning to build. You must make a wise choice so that you benefit in the end. Among the crowded market, two of the frameworks stand out. We will make a comparison between Ember.js and Vue.js.

Why Do You Select A Particular Framework?

Before we start comparing the two frameworks, we should understand the factors that lead to the choice of a framework. Each developer chooses a framework before he or she goes to work on an app. Let us see the reasons for the selection.

● The codes must be easy to understand and transparent.

● The framework should give the maximum power with the least amount of coding.

● The framework should provide a well laid out structure to work on.

● Does the framework support an in-built router or an external plug-in router?

● The framework should be able to transfer more data on a full page-load so that it becomes a single-page app. A single-page app is more beneficial for the application.

● In single page architectures if there is a need for users to share links to sub-screens within the interface, then the framework should have the capacity to route based on the URL.

● A tighter template option can help in enabling two-way binding.

● The framework should not conflict any third-party library.

● Testing the codes inside the framework should be easy.

● The framework should provide the HTTP client service for AJAX calls

● The documentation is essential. It should be complete and up-to-date.

● The framework should be compatible with the latest version of the browser.

● The framework has to fulfill the above conditions for easy construction of the app. You must ensure that the framework you choose meets the conditions.

Vue.js Explained

Developers are always looking at new frameworks to build their apps. The main requirements are speed and low cost. The framework should be easy to use by even new developers. You should be able to use it at low cost. Other considerations are about simple coding, proper documentation, etc.

Vue.js combines a lot of good when it comes to software language for web app development. The architecture of Vue.js is easy to put in use. The apps developed using Vue.js are easy to integrate with new apps.

Vue.js is a very lightweight framework. It makes it fast to download. It is also much faster than other frameworks. The single-file component nature of the framework is also beneficial. The size has made it very popular.

You can further decrease weight. With Vue.js you can separate the template-to-virtual DOM and compiler. You can only deploy the minified and zipped interpreter which is only 12 KB. You can compile the templates in your machine.

Another significant advantage of Vue.js is that it can integrate easily with existing applications created with JavaScript. It will make it easy for using this framework to make changes to applications already present.

Vue.js also integrates easily with other front-end libraries. You can plug in another library and make up for any deficiency in this framework. This feature makes this tool a versatile one.

Vue.js uses the method of rendering on the streaming-side server. You can render your component and get a readable stream. You can then send this to the HTTP server. It makes the server highly responsive. Your users will get the rendered content very quickly.

Vue.js is very SEO friendly. As the framework supports server-side rendering, the views are rendered directly on the server. The search engines list these.

But the most important thing for you is the ease with which you can learn Vue.js. The structure is elementary. Even new developers will find it easy to use it to build their apps. This framework helps in developing both small and large templates. It helps to save a lot of time.

You can go back and check your errors very easily. You can travel back and inspect all the states apart from testing your components. It is another important feature as far as any developer is concerned.

Vue.js also has very detailed documentation. It helps in writing your applications very quickly. You can build a web page or app with the basic knowledge of HTML or JavaScript.

● Vue.js has pure architecture. It helps in integration with other apps

● Vue.js is lightweight and fast. It can be made lighter by deploying only the interpreter

● You can separate the compiler and the template-to-virtual DOM.

● Due to smooth integration, you can use this to make changes to existing apps

● To make up for any shortfall, you can plug-in any library and makeup.

● As Vue.js uses streaming-side server rendering, your users can get quick responses.

● The server-side rendering also helps in being ranked higher by search engines.

● It has a simple structure. Easy to use for any new developer

● You can go back and check and correct your errors.

● You can check all the existing states.

● Detail documentation also helps build the web page or application very quickly.

Ember.js Decoded

Ember.js is an MVVM model framework. It is open-source software. This platform is mostly used for creating complex multi-page applications. It maintains up-to-date features without discarding any of the old features.

With this framework, you have to follow the architecture of the framework strictly. The JS framework is very tightly organized. It reduces the flexibility that other frameworks might offer.

There is a very refined and developed control system for its platforms and tools. You can integrate it with the new version with the tools provided. There is strict guidance about avoiding outdated APIs.

You can understand Ember’s APIs easily. They are also easy to work. You can make use of highly complex functionalities simply and straightforwardly.

The performance is better as similar jobs are processed together. It creates batches of similar bindings and DOM updates to improve the performance. It means that the browser needs to process them in one go. It will avoid recomputing for each task, wasting a lot of time.

You can write the codes in a simple manner and modules. You can use any of Ember’s APIs. It is possible due to the presence of Promises everywhere.

Ember comes with a well-written guide. The API is recorded in a useful manner. It is a front-end framework that is loaded. Ember has a router, pipeline, services, etc. of its own.

The basis for views, controllers, models, and framework is the Ember Object Model. All components come from the same objects. The framework is firm and steady. The reason is that all elements have similar jobs and characteristics.

Ember has made the general application, organization, and structure clear so that you don’t make any mistakes. You will have no chance to complicate the application unnecessarily. If you have to go out of the defined limits, you will have to force your way out.

The language used for templating in Embers is Handlebars. This language helps Embers to keep its logic out of view. The clean syntax of Handlebars makes it easy for you to read and understand the templates. Handlebar templates are faster to load.

Another advantage you gain from Handlebar is that you don’t have to update your template every time you add or remove data from the page. It will be done automatically by the language itself.

A community that is continually improving the framework supports Ember. They are updating the framework with the latest technology. They also make sure that backward compatibility is possible.

● Ember.js is an open-source MVVM model framework suitable for complex multiple-page applications.

● It offers both the latest and old features.

● It has a very tightly structured framework which doesn’t offer much flexibility

● A very refined control system helps you to integrate with new versions without any problem.

● There is strict guidance about avoiding outdated API versions.

● Ember’s APIs help you to use complex functionalities in a simple manner

● There is no recomputing for each task as the framework allows the browser to do similar functions together.

● Promises allow you to write modular and straightforward code using any API of Ember.js.

● Ember.js is a fully loaded, front-end framework.

● The framework is stable because all components have the same functionalities and properties.

● It has well-defined limitations which will prevent your complicating your application

● Handlebars, the language used by Ember.js allows you to read and understand templates easily. It also helps to load the templates faster.

● Handlebars will ensure to update the template every time you add or remove data.

● Ember.js has an active community that updates the framework regularly and facilitates backward compatibility.

A Comparison Between Ember.js And Vue.js

This article intends to compare the features of both frameworks. Let us see how the characteristics of these frameworks compare. It will help you to make use of the right framework for your web application.

When you need a modern engine for an old application, it is Vue.js which will help you. It combines the best properties of other frameworks. Vue.js is a developing framework. A ready-to-use library of interface elements does not exist. However, many third-party libraries can help you.

Ember.js offers you a well-organized and trustworthy framework. When the development team is big, this is the framework that suits best. It allows everyone to understand the written code and contribute to a common project. The technology will be up-to-date, and the platform will be stable.

Vue.js can help you use the syntax of different kinds. It helps in writing the codes with ease. It is also an SEO friendly framework. Ember is a fully loaded front-end framework and can help you develop the applications very fast. But it is not suitable for developing small projects.

It is not easy to say this is better than that. It will depend on what kind of project you have undertaken. Both have their pluses and minuses. The below table will help in a better comparison.

Final Thoughts

It is not easy to conclude as to which is better. It all depends on the application that you want to develop. Both frameworks are developing. Both are getting updates. Both the communities are working on the frameworks.

While Vue.js is more comfortable for writing codes, Ember is a full-stack framework allowing the development of apps very fast. It is suitable for big projects. It is too complicated to be used for smaller projects.

We hope you had a great time reading this article. If you’ve any questions or suggestions related to this blog, then feel free to ask them in the comment section. Thank You.!