Get the string value of an attachment (which must be a text-formatted file, like .txt, .csv. or .xml) in ServiceNow

global.getAttachmentStringByName.js

var tableName = 'incident';
var sysIDOfRecord = '755d52b137b0b30090b68cf6c3990e6f';
var fileNameSansExtension = 'example text doc'; //Full file name: example text doc.txt

var grRecordWithAttachment = new GlideRecord(tableName);
grRecordWithAttachment.get(sysIDOfRecord);

var gsa = new GlideSysAttachment();
//ONLY works in global
var textVal = gsa.get(grRecordWithAttachment, fileNameSansExtension); 

gs.print(textVal);