How does Vue implement component nesting and component style management?

Vue.js is a lightweight JavaScript framework that features data-driven, responsive update views. The core concept of Vue.js is componentization. Components can be buttons, forms, modal boxes, etc., which can be freely combined and split into smaller components. The component nesting and style management of Vue.js are essential knowledge points in component development. This article will explain in detail how to implement component nesting and style management in Vue.

Component nesting

Component nesting refers to placing one component inside another component to form a parent-child component relationship, passing data to the child component through the parent component, and the child component can also send data to the parent component. Components pass data to achieve communication between components. Vue.js is very convenient to implement component nesting. You only need to introduce the template of the child component inside the parent component. The following is a simple example:

The above code is a parent component, introduce the sub-component throughimport, and then register the sub-component incomponents. Use child components within parent components. Component nesting can be achieved by introducing the template of the child component in the parent component using.

In child components, we usually get data from the parent component. Data transfer between parent and child components in Vue.js is mainly implemented in two ways:propsand$emit.propsmeans that the parent component passes data to the child component, and the child component obtains the data passed by the parent component by receivingprops. The following is a simplepropsexample:

The above code is a subcomponent that defines a namednamethroughpropsAttribute, when the parent component passes data to the child component, it passes it through thenameattribute. In the template of the child component, you can obtain the data passed by the parent component through{{ name }}.

When passing data from the parent component to the child component, you can pass the data through thev-binddirective. As shown below:

In the parent component, we define a variable namedfatherNameto store the name of the parent component. In the child component, we receivefatherNameviaprops.

Component style management

Component style management refers to how to manage the styles of components in Vue.js to ensure that the styles of each component do not affect each other and are easy to maintain. Vue.js provides two ways to manage component styles: scope styles and CSS Modules.

Scope style

Scope style refers to using thescopedattribute to define the style in the component, so that the component style is only valid for the current component. For example:

In this component, we added thescopedattribute to the style tag, that is,style scoped. The style defined in this way is only effective for the current component and will not affect other components or global styles.

There is a disadvantage of using scope styles: deep selectors are not supported. In a component, if you want to use a deep selector, you must add/deep/or >>> before the selector, as shown below: >>>

In the above code, we use/deep/ .sub-componentin the style definition of.component, and in the style of.sub-title >>> is used in the definition. This allows you to define depth selectors in scope styles. >>>

CSS Modules

CSS Modules is a modular CSS solution that can modularize and name CSS to ensure that the style of each component is independent. Vue.js provides support for CSS Modules, and we can use independent CSS Modules in each component.

First, we need to installcss-loaderandstyle-loader, and add configuration about CSS Modules in the Webpack configuration file:

// webpack.conf.js module.exports = { // ... module: { rules: [ { test: /.css$/, loader: 'style-loader!css-loader?modules' }, { test: /.vue$/, loader: 'vue-loader', options: { cssModules: { localIdentName: '[name]-[hash]', camelCase: true } } } ] } // ... }

In the above code, we addedmodulesto the configuration ofcss-loader, indicating that CSS Modules is enabled. ThecssModulesattribute is added to the configuration ofvue-loader, indicating that CSS Modules are enabled in the single-file component of Vue.js.

In single-file components, we can specify the CSS Module name through thescopedattribute.

In the above code, we added themoduleattribute to thestyletag, indicating that this is a CSS Module. In CSS, we can define styles in the traditional way without using scoped styles or deep selectors.

When introducing CSS Module into a component, you need to use the$styleobject, as shown below:

In the above code, we use$style. titlerefers to thetitlestyle defined in this component.

Summary: Vue.js provides two ways to manage component styles: scope styles and CSS Modules. Scoped styles are suitable for simple styles, while CSS Modules are suitable for componentized applications, which modularize CSS and ensure that each component's style is independent.

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