Implement getType (precise type detection)

Implement getType(value)

typeof famously can't tell an array from an object, and says typeof null === "object". Write getType(value) that returns a precise, lowercase type string:

getType(null);        // "null"
getType([1, 2]);       // "array"
getType(new Date());  // "date"
getType(/abc/);        // "regexp"
getType("hi");         // "string"
getType(undefined);    // "undefined"

Hint: Object.prototype.toString.call(value) returns "[object Type]" for (almost) everything, that's the tool that makes this precise.