scoped CSS is a mechanism used in Vue single-file components to isolate component styles and prevent global pollution. It is implemented by adding unique attributes to component elements and rewriting the CSS selector; 1. The scoped style will not affect the subcomponents, but can be penetrated through ::v-deep or :deep(); 2. scoped and module cannot be shared, and module improves encapsulation and maintainability through class name mapping variables; 3. scoped does not affect the introduction of preprocessor and external CSS files, and controls the slot content styles for limited control, and needs to be processed in combination with global styles or penetration methods.
Using scoped CSS in Vue single file components ensures that the style only acts on the elements of the current component and avoids global contamination. This writing method is very common in actual development and is especially suitable for large projects.
What is scoped CSS?
In Vue's Single File Component (SFC), by default, the CSS in the <style></style> tag is effective globally. Once scoped attribute is added, Vue implements style isolation by adding unique attributes to the DOM elements within the component (such as data-v-f3f3eg9 ) and rewriting the CSS selector to a selector with these attributes.
For example:
<template>
<div class="example">Scoped Style</div>
</template>
<style scoped>
.example {
color: red;
}
</style> After compilation, the .example style will only be applied to the .example element inside this component.
How does scoped CSS affect child components?
The scoped style does not automatically penetrate into the child component. That is to say, even if you write the .btn style in the parent component, elements with the same class name will not be affected in the child component.
But sometimes you do need to control the style of the child component in the parent component, and you can "penetrate" the scoped style by using ::v-deep or :deep() .
:deep(.child-component .some-class) {
color: blue;
}or:
::v-deep .child-component .some-class {
color: blue;
}Note: Be cautious when using this method to avoid damaging the isolation advantages brought by style packaging.
Can scoped and module be used together?
scoped and module cannot be used at the same time. They are two different CSS modular solutions:
-
scopedisolates styles through attribute selectors; -
modulemaps class names into module variables and needs to be called in the template through$style.
for example:
<template>
<div :class="$style.redText">Red Text</div>
</template>
<style module>
.redText {
color: red;
}
</style>This method is safer, more maintainable, but it is also more cumbersome.
Some small details of scoped style
- If you use
<style lang="scss" scoped></style>, no problem, the preprocessor will not affect the scoped behavior. - scoped will not prevent the influence of introducing external CSS files. For example, if you write
@import "global.css"in scoped style, then the style in global.css will still take effect globally. - scoped has limited style control over
<slot></slot>content. If you want slot content to inherit the style of the parent component, you may need to put the relevant style globally or use::v-deep.
Basically that's it. scoped CSS is a very practical function in Vue. Understanding its working mechanism and limitations can help you write clearer and less conflict-free component styles.
The above is the detailed content of Example of using scoped CSS in a Vue component. For more information, please follow other related articles on the PHP Chinese website!
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