add abstract method
- String value
override
Add the class value to element.
add and addAll are the Dart equivalent of jQuery's addClass.
If this CssClassSet corresponds to one element. Returns true if value was
added to the set, otherwise false.
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 add multiple classes use
addAll.
Implementation
bool add(String value);