Type-safe check whether @value is an array.

Checks whether the specified @array is empty. Returns true when there are no items in the @array.

Type-safe check whether the specified @array contains only elements of type T. The specified @checkType function is invoked on every item in the @array to determine whether it is of the expected type.

Type-safe check whether @value is a Function.

Type-safe check whether @value is missing. @value is considered missing when it is either null or undefined.

Type-safe check whether @value is null.

Type-safe check whether @value is a number.

Type-safe check whether @value is of type Object.

Checks whether @value is one of the specified @options. Returns true when one of the @options is strictly equal to @value.

Checks whether @value is present. @value is considered present when it is neither null nor undefined.

Type-safe check whether @value is a string.

Type-safe check whether @value is undefined.