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JSR Working Group Kicks Off with Ambitious Roadmap and Plans for Open Governance
At its inaugural meeting, the JSR Working Group outlined plans for an open governance model and a roadmap to enhance JavaScript package management.
JSS (JavaScript Style Sheets) is a library for generating CSS styles with JavaScript. It allows you to define styles in a JavaScript object and apply them to your components, making it easier to manage and maintain styles in a JavaScript-centric development environment.
Creating Styles
This feature allows you to create styles using JavaScript objects. The `createStyleSheet` method generates a stylesheet from the provided styles and attaches it to the document.
const styles = {
button: {
color: 'blue',
background: 'white',
border: '1px solid blue'
}
};
const { classes } = jss.createStyleSheet(styles).attach();
// Usage in a component
const button = document.createElement('button');
button.className = classes.button;
button.textContent = 'Click me';
document.body.appendChild(button);
Dynamic Styles
This feature allows you to create dynamic styles that can change based on props or state. The `update` method is used to update the styles with new values.
const styles = {
button: {
color: props => props.color,
background: 'white',
border: '1px solid blue'
}
};
const sheet = jss.createStyleSheet(styles);
const { classes } = sheet.update({ color: 'red' }).attach();
// Usage in a component
const button = document.createElement('button');
button.className = classes.button;
button.textContent = 'Click me';
document.body.appendChild(button);
Theming
This feature allows you to create themes that can be applied to your styles. The styles can reference theme variables, making it easy to switch themes or update theme values.
const theme = {
primaryColor: 'blue',
secondaryColor: 'green'
};
const styles = theme => ({
button: {
color: theme.primaryColor,
background: 'white',
border: `1px solid ${theme.primaryColor}`
}
});
const sheet = jss.createStyleSheet(styles(theme)).attach();
const { classes } = sheet;
// Usage in a component
const button = document.createElement('button');
button.className = classes.button;
button.textContent = 'Click me';
document.body.appendChild(button);
Styled-components is a library for styling React components using tagged template literals. It allows you to write actual CSS code to style your components and supports theming and dynamic styling. Compared to JSS, styled-components is more tightly integrated with React and uses a different syntax for defining styles.
Emotion is a library designed for writing CSS styles with JavaScript. It provides both a styled API similar to styled-components and a css API for defining styles as objects. Emotion is known for its performance and flexibility, offering a similar feature set to JSS but with a different API and additional performance optimizations.
Aphrodite is a library for styling React components with JavaScript. It allows you to define styles as JavaScript objects and provides support for media queries and pseudo-selectors. Aphrodite is simpler and more lightweight compared to JSS, but it may lack some of the advanced features and flexibility that JSS offers.
Why do we need transpilers like sass or stylus when we can use javascript to do the same and much more?
By leveraging namespaces we can solve the cascading problem better than bem and make our components truly reusable and composable.
Access css declarations and values from js without DOM round trip.
Smaller footprint because of code reuse and no vendor specific declarations
Take a look at examples directory.
Jss styles are just plain javascript objects. They map 1:1 to css rules, except of those modified by preprocessors.
Put an &
before a selector within a rule and it will be replaced by the parent selector and extracted to a separate rule.
{
'.container': {
padding: '20px',
// Will result in .container.clear
'&.clear': {
clear: 'both'
},
// Will result in .container .button
'& .button': {
background: 'red'
},
'&.selected, &.active': {
border: '1px solid red'
}
}
}
.container {
padding: 20px;
}
.container.clear {
clear: both;
}
.container .button {
background: red;
}
.container.selected, .container.active {
border: 1px solid red;
}
Inherit a rule(s) by using extend
keyword. This makes it easy to reuse code. See example.
var rules = {}
var button1 = {
padding: '20px',
background: 'blue'
}
rules['.button-1'] = button1
rules['.button-2'] = {
extend: button1, // can be an array of styles
padding: '30px'
}
.button-1 {
padding: 20px;
background: blue;
}
.button-2 {
padding: 30px;
background: blue;
}
Vendor prefixes are handled automatically using a smart check which results are cached. See example.
{
'.container': {
transform: 'translateX(100px)'
}
}
.container {
transform: -webkit-translateX(100px);
}
// Pure js
var jss = window.jss
// Commonjs
var jss = require('jss')
jss.createStylesheet([rules], [named], [attributes])
rules
is an object, where keys are selectors if named
is not truenamed
rules keys are not used as selectors, but as names, will cause auto generated class names and selectors. It will also make class names accessible via stylesheet.classes
.attributes
allows to set any attributes on style element.var stylesheet = jss.createStylesheet({
'.selector': {
width: '100px'
}
}, {media: 'print'}).attach()
<style media="print">
.selector {
width: 100px;
}
</style>
Create a stylesheet with namespaced rules.
var stylesheet = jss.createStylesheet({
myButton: {
width: '100px',
height: '100px'
}
}, true).attach()
console.log(stylesheet.classes.myButton) // .jss-0
<style>
.jss-0 {
width: 100px;
height: 100px;
}
</style>
stylesheet.attach()
Insert stylesheet into render tree.
stylesheet.attach()
stylesheet.detach()
Remove stylesheet from render tree to increase runtime performance.
stylesheet.detach()
stylesheet.addRule([selector], rule)
var button = stylesheet.addRule('.my-button', {
padding: '20px',
background: 'blue'
})
In case you have an element reference or you create elements in javascript you might want to write styles and attach them later to the element using a generated class name.
var button = stylesheet.addRule({
padding: '20px',
background: 'blue'
})
document.body.innerHTML = '<button class="' + button.className + '">Button</button>'
stylesheet.getRule(selector)
// Using selector
var rule = stylesheet.getRule('.my-button')
// Using name, if named rule was added.
var rule = stylesheet.getRule('myButton')
stylesheet.addRules(rules)
Add a list of rules.
stylesheet.addRules({
'.my-button': {
float: 'left',
},
'.something': {
display: 'none'
}
})
jss.createRule([selector], rule)
var rule = jss.createRule({
padding: '20px',
background: 'blue'
})
// Apply styles directly using jquery.
$('.container').css(rule.style)
npm i jss
# print help
jss
# convert css
jss source.css -p > source.jss
To make some realistic assumptions about performance overhead, I have converted bootstraps css to jss. In bench/bootstrap
folder you will find jss and css files. You need to try more than once to have some average value.
In my tests overhead is 10-15ms.
npm i
open test/local.html
MIT
FAQs
A lib for generating Style Sheets with JavaScript.
The npm package jss receives a total of 1,686,577 weekly downloads. As such, jss popularity was classified as popular.
We found that jss demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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