This method returns a string primitive containing the value of the object with all characters converted to lower case.
The original string is converted from arbitrary case to lower-case on a character by character basis.
The characters in the output string will be the lower case equivalents of the characters in the input string according to the rules defined by the Unicode 2.0 standard.
The Canonical Unicode 2.0 mapping will be used and therefore no special international character handling semantics take place. However non-ECMA compliant implementations may provide localization support not specified by ECMA 262.
This method is intentionally generic and may be applied to a variety of object types other than strings.
The effect of this method may depend on the locale settings in a fully localizable implementation.