Corticon.js's String attribute operators are as follows:

Name and Syntax Returns Description
Equals (used as a comparison)
<String1> = <String2> Boolean Returns a value of true if <String1> exactly matches <String2>. Both case and length are examined to determine equality. 
Equals (used as an assignment)
<String1> = <String2> String Assigns the value of <String2> to the value of <String1>.
Not Equal to
<String1> <> <String2> Boolean Returns a value of true if <String1> is not equal to <String2>.
Less than
<String1> < <String2> Boolean Returns a value of true if <String1> is less than <String2>. 
Greater than
<String1> > <String2> Boolean Returns a value of true if <String1> is greater than <String2>.
Less than or Equal to
<String1> <= <String2> Boolean Returns a value of true if <String1> is less than or equal to <String2>.
Greater than or Equal to
<String1> >= <String2> Boolean Returns a value of true if <String1> is greater than or equal to <String2>.
In (Range)
attributeReference in [ |(rangeExpression)|] Boolean Returns a value of true if attributeReference is in the range of String values from..to, and where opening and closing parentheses ( )indicate exclusion of that limit and square brackets [ ] indicate inclusion of that limit.
In (List)
attributeReference in {listExpression} Boolean Returns a value of true if attributeReference is in the comma-delimited list of literal values, defined enumeration values, or - if in use - enumeration labels.
Adding Strings
<String1> + <String2> String Concatenates <String1> to <String2>. Alternative syntax.
Size
<String>.size String Returns the number of characters in <String>.
Concatenate
<String1>.concat(<String2>) String Concatenates <String1> to <String2>.
Uppercase
<String>.toUpper String Converts all characters <String> to uppercase.
Lowercase
<String>.toLower String Converts all characters in <String> to lowercase.
To DateTime
<String>.toDateTime DateTime Converts the value in <String> to data type DateTime ONLY if date as ISO8601 string or millisecs since epoch as a string.
To Decimal
<String>.toDecimal Decimal Converts an attribute of type String to data type Decimal ONLY if all characters in <String> are numeric and contain not more than one decimal point. If any non-numeric characters are present (other than a single decimal point or leading minus sign), no value is returned.
To Integer
<String>.toInteger Integer Converts an attribute of type String to type Integer ONLY if all characters in <String> are numeric. If any non-numeric characters are present, no value is returned.
Substring
<String>.substring (<Integer1>,<Integer2>) String Returns that portion of <String> between character positions <Integer1> and Integer2>.
Equals Ignoring Case
<String1>.equalsIgnoreCase (<String2>) Boolean Returns a value of true if <String1> is the same as <String2>, irrespective of case.
Starts with
<String1>.startsWith (<String2>) Boolean Returns a value of true if the <String1> begins with the characters specified in <String2>.
Ends with
<String1>.endsWith (<String2>) Boolean Evaluates the contents of <String1> and returns a value of true if the String ends with the characters specified in <String2>.
Contains
<String1>.contains (<String2>) Boolean Evaluates the contents of <String1> and returns a value of true if it contains the exact characters defined by <String2>
Equals
<String1>.equals (<String2>) Boolean Returns a value of true if <String1> is the same as <String2>.
Index Of
<String1>.indexOf (<String2) Integer Returns the beginning character position number of <String2> within <String1>, if <String1> contains <String2>. If it does not, the function returns a value of zero.
Replace String
<String>.replaceString(stringToBeReplaced,replacementString) String Returns a new String where the instances of the String to be replaced are replaced by the value of the replacement String.
Regular expression replace String
<String>.regexReplaceString(regularExpression,replacementString) String Returns a new String where the Strings matching the regular expression are replaced by the replacement String.
Matches
<String>.matches(regularExpression:String) Boolean Returns true if the regular expression matches the String.
characterAt(index)
<String>.characterAt(index:Integer) String Returns the character at the specified position in the String.
isInteger
<String>.isInteger Boolean Determines whether "this" String contains only integer digits.
Note: This operator examines each character in a string to determine whether it is in the range 0 to 9. Therefore, the operator returns true when the entire string evaluates as a positive integer, and false when a minus sign is the first character of a string that would evaluate as a negative integer. A new extended operator could be created if the string as a whole is to be evaluated as true whether positive or negative (for example, by allowing the first character to be a minus sign.)
trimSpaces
<String>.trimSpaces String Trims leading and trailing spaces from "this" String.