toggle method Null safety
Adds the class value
to the element if it is not on it, removes it if it
is.
If shouldAdd
is true, then we always add that value
to the element. If
shouldAdd
is false then we always remove value
from the element.
If this corresponds to one element, returns true
if value
is present
after the operation, and returns false
if value
is absent after the
operation.
If this CssClassSet corresponds to many elements, false
is always
returned.
value
must be a valid 'token' representing a single class, i.e. a
non-empty string containing no whitespace. To toggle multiple classes, use
toggleAll.
Implementation
bool toggle(String value, [bool? shouldAdd]);