description

# toggle method Null safety

bool toggle (

1. String value,
2. [bool? shouldAdd]

)

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]);