A series of Document prototype functions for Adobe Extendscript

ESDocumentGetFileExtension.js

/* Get file extension of document */
Document.prototype.getFileExtension = function() {
    var str = this.fullName.fsName;
    return str.substring(str.lastIndexOf(".") + 1);
};

ESDocumentGetFileName.js

/* Get file name of document */
Document.prototype.getFileName = function() {
    var str = this.fullName.fsName;
    return str.substring(str.lastIndexOf("\\") + 1, str.lastIndexOf("."));
};

ESDocumentGetFilePath.js

/* Get full path of document */
Document.prototype.getFullPath = function() {
    return this.fullName.fsName;
};

ESDocumentGetFolderPath.js

/* Get full path of the folder of the document */
Document.prototype.getFolderPath = function() {
    var str = this.fullName.fsName;
    return str.substring(0, str.lastIndexOf("\\"));
};