vue pass class to component

This state might be data fetched through an Ajax request, user input, or any other type of data source that is made available at run time. If there is a match, it will pass it along as a normal prop. It is a very scalable and efficient solution for passing down template code from one component to another. That's where props come into the picture. This post is suited for developers of all stages, including beginners. Pass Data from Child to Parent You can send data from a child to a parent component by means of Vue’s built-in $emit () method. Instead you need to have your dynamic component in data or computed property so you can use it in a template as a prop. Introduction. firstName + ' ' + this. Instead of guessing why problems happen, you can aggregate and report on what state your application was in when an issue occurred. You can verify your version by running this command in your terminal/command prompt: A code editor; I highly recommend Visual Studio Code, Vue’s latest version, installed globally on your machine. Vue.js allows you to treat registered ViewModel constructors as reusable For any key/value pair where the value is true, it will apply the key as the classname. I am creating a new component box, for form layout. Because Vue.js applies a special logic to the class, style and ref attributes, they are not part of data.attrs, but instead you can access classes, styles and refs via data.class / data.staticClass, data.style / … For example, if you declare this component: Vue.component('my-component', { template: '

Hi

'}) Then add some classes when using it: < my-component class = "baz boo" > The rendered HTML will be: < p class = "foo bar baz boo" > Hi … In the same way that HTML elements can be placed inside of each other, Vue components can also be nested inside of each other. I'm Michael Thiessen and I write about all things VueJS here. The reason this works is that Vue will set class on the root element of MovieList directly. Yet, letting a child component modify parent data is considered an anti pattern in Vue: in this case, you should emit events and use a new Vue instance as a hub. VueJS props are the simplest way to share data between components. The products.vue file is known as a component. However, there’s a way for every Vue.js component style to cope with it. First, we need to have a list of items (data) we want to pass to the component. Vue will throw a warning if you attempt to do so. Being able to add a dynamic class name to your component is really powerful. Existing classes on this element will not be overwritten. If we convert our expressions to computed props, we can move more of the logic out of the template and clean it up: Not only is this much easier to read, but it's also easier to add in new functionality and refactor in the future. Although not strictly associated with the MVVM pattern (opens new window), Vue's design was partly inspired by it.As a convention, we often use the variable vm (short for ViewModel) to refer to a component instance.. Imagine a scenario in which the Vue slot can also access the data object in the child component from the parent component — a kind of slot with props ability. Now that we have modified the child component (BookCard.vue) to accept a prop named bookData. To make this happen, we build our components so they can be reused more than just once. This is a big change as it questions the usability of named slots, but as of this writing, slots are still very much part of the documentation. We can pass an object to :class (short for v-bind:class) to dynamically toggle classes: < One would assume you declare in a components property of parent component and then use it for el attribute but this doesn't work. In reality, what I was trying to do was a lot more complex since it involved a bunch of SCSS calculations and CSS animations, but I like keeping my articles clutter free - so bear with me. To do this, uninstall the old CLI version first: Navigate into the unzipped file and run the command to keep all the dependencies up to date. See the following JSBin as an example. We'll cover a lot of stuff in this article: Not only that, but at the end I'll show you a simple pattern for using computed props to help clean up your templates. You will need the following on your machine: Vue slots are Vue template elements created by the Vue team to provide a platform for template content distribution. When you use the class attribute on a custom component, those classes will be added to the component’s root element. How do we do this with our own custom components? To test this out, copy this new code block into your test.vue file: If you run the application, you can see that hello world is printed three times. Slots allow you to write very powerful, expressive components. The value of fontTheme is a classname that will change how our fonts look. When you set props on a component, Vue will compare those props to what the component has specified in it's props section. I'm sorry for my bad english. < template > < input v-model = " name " > < script > import Vue from 'vue' import Component from 'vue-class-component' @Component export default class HelloWorld extends Vue {firstName = 'John' lastName = 'Doe' // Declared as computed property getter get name {return this. This post is suited for developers of all stages — including beginners — though there are some prerequisites before going through this tutorial. If you have followed this post from the start, you will have the Vue starter project open in VS Code. How to do that? Positioning of content is another great use case for Vue slots. Let’s take as an example the vuetify’s button component, one of the simplest ones. Initial Data Declartion. For slots, your child component acts as the interface or structure of how you want your content arranged. We will now have to pass that data to the child component from the parent component, which in this case is BookList.vue. Static classes are the boring ones that never change, and will always be present on your component. — Writing a Single-File Component with TypeScript. Positioning of content is another great use case for Vue slots. In Vue we can add both static and dynamic classes to our components. Note: If you are coming from an Angular background, this is a similar concept to transclusion or content projection. This is because the v-bind syntax takes in whatever we pass as a Javascript value. To illustrate the simple example in the syntax section, our parent component will be the app.vue file. You can verify that you have this version by running the command below in your terminal/command prompt: 1. Otherwise, Vue will add it to the root DOM element. A simple version of this you've already seen: We can set a variable to contain the string of whatever class name we want. The second (optional) parameter is … You also saw how slots can also act as props by scoping. This will come in handy once you start using dynamic class names everywhere! For this reason, Vue provides special enhancements when v-bind is used with class and style. While the v-model directive is a powerful asset to add two-way data binding in vanilla Vue.js components, support for custom components isn’t as exercised.. Prerequisites. So if you want to add more content — say, a header, a paragraph with text, and then an unordered list — Vue lets us name the scopes so that it can identify the particular scope to display. In this tutorial, you will explore an example Vue project with a parent component … Say you have a Car component. Let’s move to the initial data declaration section. It is common convention to use dashes — or hyphens — in CSS classnames. This would also be a nasty mess when it comes time to update the list! Here, because MovieList didn't specify a class property, Vue knows that it should set it on the root element. This data could be from a database or an API. Vue Class Component already uses decorators syntax with @Component (in v8 @Options) but it would be good not to rely on it too much in a new API because of its uncertainty and to reduce the impact of potential breaking changes in the future when we adapt Vue Class Component with the latest spec. Adding a dynamic class name is as simple as adding the prop :class="classname" to your component. While all the examples on … If you know about Vue slots, you might wonder if props and slots do the same thing. 2. Naming the slots in the test.vue file will look like this: Now, you also have to label the HTML elements according to the slot name in which you want to display them. But light-theme won't be applied because !darkMode will evaluate to false. Vue provides a way to accomplish this with slots.. # Binding HTML Classes # Object Syntax. Vue also has a shorthand syntax for v-bind: What's really neat is that you can even have both static and dynamic classes on the same component. When darkMode is true, it will apply dark-theme as a dynamic class name to our element. lastName } // Declared as computed property setter set name (value) … Edit this page. But in order to write the object keys with dashes in Javascript, we need to surround it in quotes to make it a string. My favourite is to use ternaries inside of the template, which tends to be quite clean and readable. Insights that will make you a better Vue developer, Exclusive content that you can't get anywhere else, How we can use regular Javascript expressions to calculate our class, How to use dynamic class names on custom components. Copy this into the template section of your app.vue file: When Vue version 2.6 was released, it shipped with a better syntax to reference slot names from the child components called v-slot, which is meant to replace the initial slot syntax. To illustrate this, go ahead and create a data object in the child component by copying the code block below into the test.vue file: Just like normal props, the v-bind directive was used to bind the team in the data with the prop reference in the parent component. Here are a few things you should already have before going through this article: 1. If you wish to pass a number or a boolean though, you must still use a binding expression (:myProp=“boolean”). For the sake of example, let’s pretend you have a button component that you want to pass some properties that will control its height and the background color. An understanding of two-way data binding in Vue.js is suggested but not required. The LogRocket Vuex plugin logs Vuex mutations to the LogRocket console, giving you context around what led to an error, and what state the application was in when an issue occurred. If they don't set any, it will add the .default class. This let's you have some static classes for the things you know won't change, like positioning and layout, and dynamic classes for your theme: In this case, theme is the variable that contains the classname we will apply (remember, it's treating it as Javascript there). Well, the central idea of these tools or platforms is to encourage reusability and efficiency of resources. You may also want to check out the @Prop and @Watch decorators provided by Vue Property Decorator. You can just create a template and then use another component or the parent component to arrange that template as you would like it to appear in the user interface. Vue Class Component also provides a mixins helper for mixin inheritance, and a createDecorator function to create your own decorators easily. Whatever classname evaluates to will be the class name that is added to your component. The syntax looks like this: Vue.component('blog-post', { props: ['title'], template: '

{{ title }}

' }) Binding to style and class in Vue.js can be extremely handy for making styles respond to state in your application. Props deal with passing data objects from component to component, but slots deal with passing template (HTML) content instead from component to component. That’s not bad, but it’s true that passing lots of props can get a bit cumbersome and ugly. Instead, we'll dynamically generate the name of the class we want to apply. This means, that we can simply use v-bind="$attrs" to pass down the attributes that children would care about, even if the component doesn't specify them itself. There are some even more advanced things we can do with dynamic class names though... We've seen a lot of different ways that we can dynamically add or remove class names. Visual Studio Code editor or a similar code editor. However, scoped slots act exactly like props; this will be clearly illustrated in this tutorial. In this article we'll cover six of those patterns, so that you can take your slot skills to the next level. Join 7,007 Vue developers and get exclusive tips and tricks straight to your inbox, every single week. Say that we want to pass the same bunch of props in most cases: Using Props To Share Data From Parent To Child. Now we've covered the basics of dynamically adding classes to Vue components. Introduction. You want to add a class … Rather, simply pass it as a normal HTML attribute, such as myProp=“string”. Alright, so this would be Published Jun 23, 2018. Eventually the expressions in our template will get too complicated, and it will start to get very messy and hard to understand. We get light-theme as our dynamic classname instead of dark-theme. If they set it to primary, it will add the .primary class. We all want to write less code, but get more done. And, as we can see, a component represents a set of HTML, complete with CSS for that HTML and even behavior for those elements, which we'll learn about soon.. Instead it returns the root component instance. This post will introduce you to how data can be passed from the parent component to child components in Vue.js using Vue slots. The problem is, that this component won’t be useful unless you can pass data to it, such as the time, title, location and description of the specific event we want to display. With Vue slots, you can structure an HTML interface (like with TypeScript), which you can then use as a guide to build out your components by template injection. If we wanted to do this for our Button component, we could do something simple like this: Now, whoever is using the Button component can simply set the theme prop to whatever theme they want to use. Then, in our template, we can give those attributes values and — BAM — we’re passing data from a parent to a child component! We can even use an object to define the list of dynamic classes, which gives us some more flexibility. Unlike most of the application methods, mount does not return the application. This post has introduced you to slots in Vue.js and how they are important to content injection. You can find the complete code for this tutorial here. Open your app.vue file and copy in this code block: The child component is going to be the test component, so copy the code block below in the test.vue file: Run the application in the dev environment with this command: Vue allows for more than one slot for a component, which means that you can have any number of slots you want. It lets you write custom themes more easily, add classes based on the state of the component, and also write different variations of a component that rely on styling. If we wanted to add a static class, it's exactly the same as doing it in regular HTML: Dynamic classes are very similar, but we have to use Vue's special property syntax, v-bind, in order to bind a Javascript expression to our class: You'll notice we had to add extra quotes around our dynamic class name. How to Dynamically Add a Class Name in Vue - Michael Thiessen The opposite happens when darkMode is set to false. The first parameter of $emit is the event that should be listened for in the parent component. You saw how to set it up, and even how to have more than one slot for a component. It is a very scalable and efficient solution for passing down template code from one component to another. The prop is used to pass in an initial value; the child component wants to use it as a local data property afterwards. The way it works is that you define your data on the parent component and give it a value, then you go to the child component that needs that data and pass the value to a prop attribute so the data becomes a property in the child component. You probably don't want to spend your whole day writing out every single one, along with the logic to turn it on and off. In the code below, Vue.component is the component, and new Vue is called the instance. It's one of the best tricks for cleaning up your Vue components! With Vue slots, you can structure an HTML interface (like with TypeScript), which you can then use as a guide to build out your components by template injection. I've said it before and I'll say it again: Computed properties are the most important feature in Vue. So, instead of a parent component template with slots like this: From version 3.0 (which should be released before the end of the year), it will now look like this: Notice that aside from the minor change in the string from slot to v-slot, there is also a major change: the v-slot can only be defined on templates instead of on any HTML element. LogRocket is like a DVR for web apps, recording literally everything that happens in your Vue apps including network requests, JavaScript errors, performance problems, and much more. Vue CLI 3.0 installed on your machine. It is an implementation of the a content distribution API that was inspired by the Web Components spec draft. Exploring urql from an Apollo perspective, Using Firebase Authentication in NestJS apps, Creating physics-based animations in React with renature, Why I (finally) switched to urql from Apollo Client. Modernize how you debug your Vue apps - Start monitoring for free. This has been causing me grief too, I'm having to use props with un-obvious names to pass class attributes down to my reusable components. If there are lots of different classes you want to add dynamically, you can use arrays or objects. Both are useful, but we'll cover arrays first. There are many different ways to conditionally bind classes in Vue, and they're worth exploring. Passing classes, styles and refs to functional components. Node.js version 10.x and above installed. Content distribution is important for many reasons, some of which have to do with structure. Changing Passed Data. Oftentimes you will need to allow your parent Vue components to embed arbitrary content inside of child components. Of course, there is a lot more we can do here with dynamic classes in Vue. Props are custom attributes that we can give to a component. Similar to the logic we implemented before, we want to switch between these themes based on the value of darkMode. Let's look at an example of the object syntax: Our object contains two keys, dark-theme and light-theme. It can look like this: The parent component (where the HTML content to be injected into the child component resides) can look like this: This combination will return a user interface that looks like this: Notice how the slot on it own serves as a guide for where and how content will be injected — that is the central idea. Primitive values passed to a child component through props cannot be changed. Vue 2.x October 2017 UPDATE With the new version, .sync has been first deprecated, then re-introduced (see here). From our previous example, we can still switch between light and dark themes using our darkMode variable. A class component is a TypeScript class … In addition to strings, the expressions can also evaluate to objects or arrays. Typically, we’ll have one instance and several components, as the instance is the main app. Using Vue slots, you can pass or distribute HTML code across various components in your project. You can have more than one instance in an application. Open your app.vue file and copy the code block below into the template section: If you run your application, you will see that the data object was successfully passed to the parent component. Since v-bind will accept any Javascript expression, we can do some pretty cool things with it. Since we are just evaluating a javascript expression, you can combine the expressions we just learned with the array syntax: We are using the array to set two dynamic class names on this element. Passing custom component to prop is little bit tricky. Passing Data to Child Components with Props. 1. Let's say that we have a custom component that we are using in our app: If we want to dynamically add a class that will change the theme, what would we do? More about me. On the other hand, dynamic classes are the ones we can add and remove things change in our application. Go ahead and enjoy implementing slots in your workflow. Adding the quotes makes sure that Vue will treat it as a string. For example, we … Let's say you have a Button component, with 20 different CSS styles for all of your different types of buttons. With that in mind, slots and props are similar. Luckily, we have an easy solution for that. Sure, scoped slots let you create some nice abstractions and watchers are useful too. Node.js version 10.x and above installed. The previous example would turn into: < template > < script > export default { … The Initial data can … But what about dynamically generating the class name itself? In this article, you will learn about how to add the v-model directive for custom components in Vue.js. yyx990803 you stated "When authoring components, I don't think it's a good idea to encourage the user to directly style the component via classes or inline styles." But I don't think anything comes close to how valuable computed props are. Vue, how to use a prop as the class name Sometimes you pass a prop to a component, and you want to use that prop value as the class name. Props are custom attributes that which we can register on a component. This pattern — moving things from the template into computed props — works with all sorts of things as well. We just add the :class property like before! If you've got a Vue component that won't update the way you expect it to, this debugging guide will help you to quickly identify and fix the problem. Vue’s latest version installed globally on your machine 3. S move to the component eventually the expressions in our application as a prop for mixin inheritance, a... Have to do with structure when you use the class name that is added to the child acts... Our application modified the child component through props can not be overwritten solution for passing down template code one... You need to have a list of items ( data ) we want to check out the prop! The template, which in this article, you can pass or distribute code! I am creating a new component box, for form layout for all of your types... Objects or arrays this happen, we can give to a component lastname } Declared... An easy solution for passing down template code from one component to another Vue we can add both static dynamic. Scalable and efficient solution for passing down template code from one component to another dark themes using darkMode... Generating the class we want to add the.default class think anything comes close to how valuable computed —! You create some nice abstractions and watchers are useful, but get more done evaluate objects! The same bunch of props in most cases: Introduction light-theme wo n't be applied because darkMode... Generating the class name to our element of the vue pass class to component syntax: our object contains two keys dark-theme. Vue.Js using Vue slots an API pattern — moving things from the parent component is set to...., styles and refs to functional components remove things change in our application is great. Name is as simple as adding the quotes makes sure that Vue will add the directive. Add a dynamic class names everywhere can use it in a components property of parent component vue pass class to component this post introduced... Your Vue components components in your workflow common convention to use ternaries inside of the best for. Report on what state your application was in when an issue occurred how valuable props... Of buttons various components in your project feature in Vue we can even use an object to the! The template into computed props are, so this would also be a nasty mess when it comes to! Template as a string with structure Vue we can give to a child from. Ternaries inside of child components using dynamic class names everywhere convention to use dashes — or hyphens in... You should already have before going through this article we 'll dynamically generate the name of the a distribution! Get light-theme as our dynamic classname instead of guessing why problems happen, we need to allow parent... With 20 different CSS styles for all of your different types of buttons works all. Do with structure darkMode will evaluate to false on your machine 3 the template into computed —... Code for this reason, Vue will throw a warning if you are coming from an Angular background this. Our previous example, we build our components here with dynamic classes are the boring ones that never change and! On the root element classes in Vue is true, it will apply the key as the instance the. Css classnames listened for in the parent component will be clearly illustrated in article. Is used with class and style it to the child component ( BookCard.vue ) to accept prop... Slots act vue pass class to component like props ; this will be added to the root DOM element components in Vue.js is but... Lot more we can add both static and dynamic classes to Vue.! That is added to your component modified vue pass class to component child component from the parent component and then use it in template... Clean and readable interface or structure of how you want your content.... Custom components is suited for developers of all stages — including beginners — though there are many different to... For cleaning up your Vue components will treat it as a string you wonder... The simplest way to accomplish this with slots a dynamic class name itself adding classes our... The initial data declaration section come in handy once you start using class... Name that is added to the component class attribute on a component will it. Parent component, with 20 different CSS styles for all of your different types of buttons classes to element! Have modified the child component ( BookCard.vue ) to accept a prop named bookData nice. All sorts of things as well previous example, we build our components so can... Can add both static and dynamic classes, which in this article: 1 our components arranged. Come in handy once you start using dynamic class names everywhere this data could be from a database or API! Event that should be listened for in the syntax section, our component... It will start to get very messy and hard to understand however, slots. Value is true, it will add the v-model directive for custom components in Vue.js how! If props and slots vue pass class to component the same bunch of props in most cases: Introduction machine... 'Ve covered the basics of dynamically adding classes to our element, slots! Already have before going through this tutorial here assume you declare in a template as Javascript. Project open in VS code, the central idea of these tools or platforms is to use ternaries inside the! Write about all things vuejs here class on the value of darkMode adding classes to components... Tends to be quite clean and readable the central idea of these tools or is... Element of MovieList directly @ prop and @ Watch decorators provided by Vue property Decorator the! Binding in Vue.js is suggested but not required the ones we can on. Of $ emit is the event that should be listened for in the parent component to is! Editor or a similar code editor or a similar code editor of in. Name that is added to your component Studio code editor comes time to update the list modified the child from... Classname that will change how our fonts look important feature in Vue we want to between... To embed arbitrary content inside of child components accomplish this with slots will be clearly illustrated in this:. Your parent Vue components to embed arbitrary content inside of child components you start using dynamic name. What about dynamically generating the class attribute on a custom component, 20! Component style to cope with it darkMode is set to false will vue pass class to component clearly illustrated this. Before, we need to have your dynamic component in data or computed property setter set (! Your different types of buttons as well Thiessen and i 'll say it again: computed are. Objects or arrays class names everywhere from a database or an API in an application will always be present your. A classname that will change how our fonts look a similar concept transclusion... Our element to transclusion or content projection tricks for cleaning up your Vue components to embed arbitrary content of... For el attribute but this does n't work i do n't set,... Add and remove things change in our application added to the child component acts as the classname there lots., styles and refs to functional components expressions can also act as props scoping! Assume you declare in a template as a dynamic class name to your component specified in it props. Common convention to use dashes — or hyphens — in CSS classnames 's look at an example vuetify! Pass as a string in Vue.js useful too look at an example the ’. Never change, and will always be present on your machine 3 for in the section! So they can be reused more than one slot for a component learn about to... Distribution API vue pass class to component was inspired by the Web components spec draft version running! Classes in Vue get exclusive tips and tricks straight to your inbox, every single week introduce to. The complete code for this reason, Vue provides a mixins helper for inheritance. When you use the class attribute on a custom component to child components in Vue.js using slots... Tutorial here scoped slots let you create some nice abstractions and watchers are useful, get! Because! darkMode will evaluate to false provides a way to Share data from parent to child.! Simple example in the parent component and then use it in a components property parent... More than just once but light-theme wo n't be applied because! darkMode will evaluate to false not! Distribution is important for many reasons, some of which have to pass to the has... Still switch between light and dark themes using our darkMode variable it for el attribute but this does n't.. All of your different types of buttons those patterns, so this would be. For passing down template code from one component to another set it primary... We need to allow your parent Vue components to embed arbitrary content inside of the template, which this... Patterns, so this would be now that we can do some pretty cool things with it structure how! Already have before going through this article we 'll dynamically generate the name of the class attribute a..., some of which have to do with structure all want to pass that data the. Write about all things vuejs here do so with that in mind, slots props... Need to allow your parent Vue components article we 'll cover six of those patterns, so this also! In mind, slots and props are custom attributes that we want to pass the same bunch of props most! ; this will come in handy once you start using dynamic class name itself by running the command below your! Because! darkMode will evaluate to false pass or distribute HTML code across various components in your terminal/command prompt 1. Instance and several components, as the interface or structure of how you want to switch between and...

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