Vue Slot Pass Props

In terms of final output, slots perform a similar function as props in Vue — getting data from a parent component to a child component. However, whereas props pass data values to the component, slots can just pass direct template code. I think that this comes with a few benefits depending on the situation. When crafting components with Vue.js you can go multiple ways. You can go with the props based approach or you can choose the slot based solution. If you’re using props, things can quickly get out. I found a way to get access tot the scoped slot props outside of the slot but it’s a hack. Make a component to just receive a prop( the scoped slot provided prop). And do with it whatever you want. But there has to be a better way.

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All developers using component-based architectures, such as Vue’s and React’s, know that creating reusable components is hard, and most of the time you end up having a lot of props in order to make it easier to control and customize a component from the outside.

That’s not bad, but it’s true that passing lots of props can get a bit cumbersome and ugly. However, there’s a way for every Vue.js component style to cope with it.

Let’s take as an example the vuetify’s button component, one of the simplest ones. Say that we want to pass the same bunch of props in most cases:

It could make sense to have them in a separate file, let’s call it props.js:

JSX and Render Functions

Since they give you more power and flexibility when it comes to rendering, it’s fairly easy to pass multiple props at once.

In a render function:

And in JSX:

Using a Vue.js template

What about using the Vue.js DSL (or template)? No worries, that’s also possible. All you need to do is to use the v-bind directive. Given an object that you must define in the data option of your component it will bind all props:

With this trick you won’t need to fill your template with repeated props at several places in your app, while still being able to use the beloved template tag.

Wrapping Up

Passing multiple props to a component can be simplified using the examples mentioned in this article. This is especially useful for presentational and third party components that have lots of props.

Keep in mind that the examples used here are merely educational. If you want to stay DRY (Don’t Repeat Yourself) there could be better approaches depending on the specific case, such as creating your own wrapper components.

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This page assumes you’ve already read the Components Basics. Read that first if you are new to components.

Prop Casing (camelCase vs kebab-case)

HTML attribute names are case-insensitive, so browsers will interpret any uppercase characters as lowercase. That means when you’re using in-DOM templates, camelCased prop names need to use their kebab-cased (hyphen-delimited) equivalents:

Again, if you’re using string templates, this limitation does not apply.

Prop Types

So far, we’ve only seen props listed as an array of strings:

Usually though, you’ll want every prop to be a specific type of value. In these cases, you can list props as an object, where the properties’ names and values contain the prop names and types, respectively:

This not only documents your component, but will also warn users in the browser’s JavaScript console if they pass the wrong type. You’ll learn much more about type checks and other prop validations further down this page.

Passing Static or Dynamic Props

So far, you’ve seen props passed a static value, like in:

You’ve also seen props assigned dynamically with v-bind, such as in:

In the two examples above, we happen to pass string values, but any type of value can actually be passed to a prop.

Passing a Number

Passing a Boolean

Passing an Array

Passing an Object

Passing the Properties of an Object

If you want to pass all the properties of an object as props, you can use v-bind without an argument (v-bind instead of v-bind:prop-name). For example, given a post object:

The following template:

Will be equivalent to:

One-Way Data Flow

Vue Slot Pass Props For Sale

All props form a one-way-down binding between the child property and the parent one: when the parent property updates, it will flow down to the child, but not the other way around. This prevents child components from accidentally mutating the parent’s state, which can make your app’s data flow harder to understand.

In addition, every time the parent component is updated, all props in the child component will be refreshed with the latest value. This means you should not attempt to mutate a prop inside a child component. If you do, Vue will warn you in the console.

There are usually two cases where it’s tempting to mutate a prop:

1. The prop is used to pass in an initial value; the child component wants to use it as a local data property afterwards. In this case, it’s best to define a local data property that uses the prop as its initial value:

2. The prop is passed in as a raw value that needs to be transformed. In this case, it’s best to define a computed property using the prop’s value:

Note that objects and arrays in JavaScript are passed by reference, so if the prop is an array or object, mutating the object or array itself inside the child component will affect parent state.

Prop Validation

Components can specify requirements for their props, such as the types you’ve already seen. If a requirement isn’t met, Vue will warn you in the browser’s JavaScript console. This is especially useful when developing a component that’s intended to be used by others.

To specify prop validations, you can provide an object with validation requirements to the value of props, instead of an array of strings. For example:

When prop validation fails, Vue will produce a console warning (if using the development build).

Note that props are validated before a component instance is created, so instance properties (e.g. data, computed, etc) will not be available inside default or validator functions.

Type Checks

The type can be one of the following native constructors:

• String
• Number
• Boolean
• Array
• Object
• Date
• Function
• Symbol

In addition, type can also be a custom constructor function and the assertion will be made with an instanceof check. For example, given the following constructor function exists:

You could use:

to validate that the value of the author prop was created with new Person.

Non-Prop Attributes

A non-prop attribute is an attribute that is passed to a component, but does not have a corresponding prop defined.

While explicitly defined props are preferred for passing information to a child component, authors of component libraries can’t always foresee the contexts in which their components might be used. That’s why components can accept arbitrary attributes, which are added to the component’s root element.

For example, imagine we’re using a 3rd-party bootstrap-date-input component with a Bootstrap plugin that requires a data-date-picker attribute on the input. We can add this attribute to our component instance:

And the data-date-picker='activated' attribute will automatically be added to the root element of bootstrap-date-input.

Replacing/Merging with Existing Attributes

Imagine this is the template for bootstrap-date-input:

To specify a theme for our date picker plugin, we might need to add a specific class, like this:

In this case, two different values for class are defined:

• form-control, which is set by the component in its template
• date-picker-theme-dark, which is passed to the component by its parent

For most attributes, the value provided to the component will replace the value set by the component. So for example, passing type='text' will replace type='date' and probably break it! Fortunately, the class and style attributes are a little smarter, so both values are merged, making the final value: form-control date-picker-theme-dark.

Disabling Attribute Inheritance

If you do not want the root element of a component to inherit attributes, you can set inheritAttrs: false in the component’s options. For example:

This can be especially useful in combination with the $attrs instance property, which contains the attribute names and values passed to a component, such as:

With inheritAttrs: false and $attrs, you can manually decide which element you want to forward attributes to, which is often desirable for base components:

Note that inheritAttrs: false option does not affect style and class bindings.

Vue Slot Pass Props Games

This pattern allows you to use base components more like raw HTML elements, without having to care about which element is actually at its root:

Vue Props Update