ГурантКак вернуть символ по его ASCII-коду в JScript?
Вроде оно

автор fromCharCode Method
Returns a string from a number of Unicode character values.

String.fromCharCode([code1[, code2[, ...[, codeN]]]])

Arguments
String

Required. The String object.

code1, . . . , codeN

Optional. A series of Unicode character values to convert to a string. If no arguments are supplied, the result is the empty string.

Remarks
A String object need not be created before calling fromCharCode.

In the following example, test contains the string "plain":

var test = String.fromCharCode(112, 108, 97, 105, 110);