how can i set max and min widht in js with media queries code example

Example: what is a max and min width media query

/* What this query really means, is If [device width] is less than or equal to 600px, then do */
@media only screen and (max-width: 600px)  {...}

/* What this query really means, is If [device width] is greater than or equal to 600px, then do */
@media only screen and (min-width: 600px) {...}