Changes

JavaScript variable names are made up of letter, numbers and underscores. They cannot contain spaces and must not begin with a number. For example ''sales_percentage'' would be a valid variable name, where as ''sales percentage'' would be invalid because it contains a space character. Similarly ''two_layers'' is valid, but ''2_layers'' is not due to the fact that it begins with a number. JavaScript variable names can be of any length, although common sense should be used to ensure excessively long name are not used.