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 plugins.
// Some random jss code example
{
'.carousel-caption': {
'position': 'absolute',
'z-index': '10',
},
'hr': {
'border': '0',
'border-top': '1px solid #eee'
},
'@media (min-width: 768px)': {
'.modal-dialog': {
'width': '600px',
'margin': '30px auto'
},
'.modal-content': {
'box-shadow': '0 5px 15px rgba(0, 0, 0, .5)'
},
'.modal-sm': {
'width': '300px'
}
}
}
I recommend to not to use this if you use jss on the client. Instead you should write a function, which makes a test for this feature support and generates just one final declaration.
In case you are using jss as a server side precompiler, you might want to have more than one property with identical name. This is not possible in js, but you can use an array.
{
'.container': {
background: [
'red',
'-moz-linear-gradient(left, red 0%, green 100%)',
'-webkit-linear-gradient(left, red 0%, green 100%)',
'-o-linear-gradient(left, red 0%, green 100%)',
'-ms-linear-gradient(left, red 0%, green 100%)',
'linear-gradient(to right, red 0%, green 100%)'
]
}
}
.container {
background: red;
background: -moz-linear-gradient(left, red 0%, green 100%);
background: -webkit-linear-gradient(left, red 0%, green 100%);
background: -o-linear-gradient(left, red 0%, green 100%);
background: -ms-linear-gradient(left, red 0%, green 100%);
background: linear-gradient(to right, red 0%, green 100%);
}
// Pure js
var jss = window.jss
// Commonjs
var jss = require('jss')
jss.createStyleSheet([rules], [named], [attributes])
rules
is an object, where keys are selectors ifnamed
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 viastyleSheet.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 style sheet with namespaced rules. For this set second parameter to true
.
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 style sheet into render tree.
styleSheet.attach()
styleSheet.detach()
Remove style sheet from render tree to increase runtime performance.
styleSheet.detach()
styleSheet.addRule([selector], rule)
Returns an array of rules, because you might have a nested rule in your style.
var rules = styleSheet.addRule('.my-button', {
padding: '20px',
background: 'blue'
})
var rules = styleSheet.addRule({
padding: '20px',
background: 'blue'
})
document.body.innerHTML = '<button class="' + rules[0].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)
jss.use(fn)
Passed function will be invoked with Rule instance. Take a look at plugins like extend
, nested
or vendorPrefixer
.
jss.use(function(rule) {
// Your modifier.
})
Things you know from stylus like @extend, nested selectors, vendor prefixer are separate plugins.
Full list of available plugins
npm install jss
#or
bower install jsstyles
# 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