I am trying to understand some uses of clsx in assigning classnames to a component in React.
The construct
className={clsx(classes.menuButton, open && classes.hide)}
is clear enough. It applies 'classes.menuButton', and also applies 'classes.hide' if the value of the boolean 'open' is true.
My question relates to this second example:
className={clsx(classes.appBar, {[classes.appBarShift]: open })}
This will apply 'classes.appBar'. But what is the meaning of the second parameter?
3 Answers
clsx is generally used to conditionally apply a given className
This syntax means that some class will only be applied if a given condition evaluates to true
const menuStyle = clsx({
[classes.root] : true, //always applies
[classes.menuOpen] : open //only when open === true
})
In this example [classes.menuOpen] (which will evaluate to something like randomclassName123) will only be applied if open === true
clsx basically outputs a string interpolation. So you don't have to necessarily use it, although is a common practice.
There are many supported syntax that you can check in the official docs
Instead of
<div className={`${classes.foo} ${classes.bar} ${classes.baz}`} />
You can use it like this
const { foo, bar, baz } = classes
const style = clsx(foo, bar, baz)
return <div className={style} />
Many people already explained it pretty well. I still wanted to add an example containing className. In the example you can see different classes, applied if a given condition evaluates to true. In the example you can apply a class with a boolean value, a boolean variable or a compared string (If match, return true).
The class classes.drawer is always applied and does not depend on a condition.
className={clsx(classes.drawer, { // classes.drawer is applied always
[classes.drawerOpen]: true, // classes.drawerOpen is applied always, bool = true
[classes.drawerClose]: !open, // you can also use boolean variable
[classes.drawerRed]: colorVar === 'red', // you can also use string variable
})}
classes.appBarShift will be applied only if open evaluates to true. If the array has more classes all of them will be applied if open evaluates to true
