The utility API is a Sass based tool to generate utility classes.
The bootstrap utilities are generated with the utility API which can be used to change or extend Bootstrap’s utility classes. If you don’t have any idea what Sass maps are, you can consult the official docs to get started.
The $utilities
map contains all utilities and is later merged with your custom $utilities
map if present. The utility map contains a keyed list of utility groups which accept the following options:
property
: Name of the property, this can be a string or an array of strings (needed for eg. horizontal paddings or margins).responsive
(optional): Boolean indicating if responsive classes need to be generated. false
by default.rfs
(optional): Variable to enable fluid rescaling. Have a look at the RFS page to find out how this works. false
by default.class
(optional): Variable to change the class name if you don’t want it to be the same as the property. In case you don’t provide the class
key and property
key is an array of strings, the class name will be the first element of the property
array.values
: This can be a list of values or a map if you don’t want the class name to be the same as the value. If null is used as map key, it isn’t rendered.print
(optional): Boolean indicating if print classes need to be generated. false
by default.All utility variables are added to the $utilities
variable. Custom utility groups can added like this:
$utilities: (
"opacity": (
property: opacity,
values: (
0: 0,
25: .25,
50: .5,
75: .75,
100: 1,
)
)
);
Output:
.opacity-0 {
opacity: 0;
}
.opacity-25 {
opacity: .25;
}
.opacity-50 {
opacity: .5;
}
.opacity-75 {
opacity: .75;
}
.opacity-100 {
opacity: 1;
}
With the class
option, the class prefix can be changed:
$utilities: (
"opacity": (
property: opacity,
class: o,
values: (
0: 0,
25: .25,
50: .5,
75: .75,
100: 1,
)
)
);
Output:
.o-0 {
opacity: 0;
}
.o-25 {
opacity: .25;
}
.o-50 {
opacity: .5;
}
.o-75 {
opacity: .75;
}
.o-100 {
opacity: 1;
}
With the responsive
option, responsive utility classes can be generated:
$utilities: (
"opacity": (
property: opacity,
responsive: true,
values: (
0: 0,
25: .25,
50: .5,
75: .75,
100: 1,
)
)
);
Output:
.opacity-0 {
opacity: 0;
}
.opacity-25 {
opacity: .25;
}
.opacity-50 {
opacity: .5;
}
.opacity-75 {
opacity: .75;
}
.opacity-100 {
opacity: 1;
}
@media (min-width: 576px) {
.opacity-sm-0 {
opacity: 0;
}
.opacity-sm-25 {
opacity: .25;
}
.opacity-sm-50 {
opacity: .5;
}
.opacity-sm-75 {
opacity: .75;
}
.opacity-sm-100 {
opacity: 1;
}
}
@media (min-width: 768px) {
.opacity-md-0 {
opacity: 0;
}
.opacity-md-25 {
opacity: .25;
}
.opacity-md-50 {
opacity: .5;
}
.opacity-md-75 {
opacity: .75;
}
.opacity-md-100 {
opacity: 1;
}
}
@media (min-width: 992px) {
.opacity-lg-0 {
opacity: 0;
}
.opacity-lg-25 {
opacity: .25;
}
.opacity-lg-50 {
opacity: .5;
}
.opacity-lg-75 {
opacity: .75;
}
.opacity-lg-100 {
opacity: 1;
}
}
@media (min-width: 1200px) {
.opacity-xl-0 {
opacity: 0;
}
.opacity-xl-25 {
opacity: .25;
}
.opacity-xl-50 {
opacity: .5;
}
.opacity-xl-75 {
opacity: .75;
}
.opacity-xl-100 {
opacity: 1;
}
}
Overriding excising utilities is possible by using the same key. For example if you want more responsive overflow utility classes you can do this:
$utilities: (
"overflow": (
responsive: true,
property: overflow,
values: visible hidden scroll auto,
),
);
Enabling the print
option will also generate utility classes for print.
$utilities: (
"opacity": (
property: opacity,
class: o,
print: true,
values: (
0: 0,
25: .25,
50: .5,
75: .75,
100: 1,
)
)
);
Output:
.o-0 {
opacity: 0;
}
.o-25 {
opacity: .25;
}
.o-50 {
opacity: .5;
}
.o-75 {
opacity: .75;
}
.o-100 {
opacity: 1;
}
@media print {
.o-print-0 {
opacity: 0;
}
.o-print-25 {
opacity: .25;
}
.o-print-50 {
opacity: .5;
}
.o-print-75 {
opacity: .75;
}
.o-print-100 {
opacity: 1;
}
}
Utilities can also be removed by changing the group key to null
:
$utilities: (
"float": null,
);