I changed the code a bit and it know works for many files:

// Copyright ZITRONE Romano Studer

// Melbourne, Australia 2012

// https://www.zitrone.com.au

// Changes to the code in order to process multyple files

//target any InDesign

#target “InDesign”

//FindChangeByList.jsx

//An InDesign CS5.5 JavaScript

/*

@@@BUILDINFO@@@ “FindChangeByList.jsx” 3.0.0 15 December 2009

*/

//Loads a series of tab-delimited strings from a text file, then performs a series

//of find/change operations based on the strings read from the file.

//

//The data file is tab-delimited, with carriage returns separating records.

//

//The format of each record in the file is:

//findType<tab>findProperties<tab>changeProperties<tab>findChangeOptions<tab>description

//

//Where:

//<tab> is a tab character

//findType is “text”, “grep”, or “glyph” (this sets the type of find/change operation to use).

//findProperties is a properties record (as text) of the find preferences.

//changeProperties is a properties record (as text) of the change preferences.

//findChangeOptions is a properties record (as text) of the find/change options.

//description is a description of the find/change operation

//

//Very simple example:

//text {findWhat:”–“} {changeTo:”^_”} {includeFootnotes:true, includeMasterPages:true, includeHiddenLayers:true, wholeWord:false} Find all double dashes and replace with an em dash.

//

//More complex example:

//text {findWhat:”^9^9.^9^9″} {appliedCharacterStyle:”price”} {include footnotes:true, include master pages:true, include hidden layers:true, whole word:false} Find $10.00 to $99.99 and apply the character style “price”.

//

//All InDesign search metacharacters are allowed in the “findWhat” and “changeTo” properties for findTextPreferences and changeTextPreferences.

//

//If you enter backslashes in the findWhat property of the findGrepPreferences object, they must be “escaped”

//as shown in the example below:

//

//{findWhat:”s+”}

//

//For more on InDesign scripting, go to https://www.adobe.com/products/&#8230;..index.html

//or visit the InDesign Scripting User to User forum at https://www.adobeforums.com

//

main();

function main(){

var myObject;

//Make certain that user interaction (display of dialogs, etc.) is turned on.

app.scriptPreferences.userInteractionLevel = UserInteractionLevels.interactWithAll;

if(app.documents.length > 0){

if(app.selection.length > 0){

switch(app.selection[0].constructor.name){

case “InsertionPoint”:

case “Character”:

case “Word”:

case “TextStyleRange”:

case “Line”:

case “Paragraph”:

case “TextColumn”:

case “Text”:

case “Cell”:

case “Column”:

case “Row”:

case “Table”:

myDisplayDialog();

break;

default:

//Something was selected, but it wasn't a text object, so search the document.

myFindChangeByList(app.documents.item(0));

}

}

else{

//Nothing was selected, so simply search the document.

var myNumberOfDocuments = app.documents.length;

//The FindChangeList.txt file used to be aquirred inside the myFindChangeByList function. Hence we would ask for it many times.

//Here we ask only one time. We use the same FindChangeList.txt file for the operation on all InDesign files.

var myFindChangeFile = myFindFile(“/FindChangeSupport/FindChangeList.txt”)

for(i=0;i<myNumberOfDocuments;i++){

myFindChangeByList(app.documents.item(i), myFindChangeFile);

}

}

}

else{

alert(“No documents are open. Please open a document and try again.”);

}

}

function myDisplayDialog(){

var myObject;

var myDialog = app.dialogs.add({name:”FindChangeByList”});

with(myDialog.dialogColumns.add()){

with(dialogRows.add()){

with(dialogColumns.add()){

staticTexts.add({staticLabel:”Search Range:”});

}

var myRangeButtons = radiobuttonGroups.add();

with(myRangeButtons){

radiobuttonControls.add({staticLabel:”Document”, checkedState:true});

radiobuttonControls.add({staticLabel:”Selected Story”});

if(app.selection[0].contents != “”){

radiobuttonControls.add({staticLabel:”Selection”, checkedState:true});

}

}

}

}

var myResult = myDialog.show();

if(myResult == true){

switch(myRangeButtons.selectedButton){

case 0:

myObject = app.documents.item(0);

break;

case 1:

myObject = app.selection[0].parentStory;

break;

case 2:

myObject = app.selection[0];

break;

}

myDialog.destroy();

myFindChangeByList(myObject);

}

else{

myDialog.destroy();

}

}

function myFindChangeByList(myObject, myFindChangeFile){

var myScriptFileName, myFindChangeFile, myFindChangeFileName, myScriptFile, myResult;

var myFindChangeArray, myFindPreferences, myChangePreferences, myFindLimit, myStory;

var myStartCharacter, myEndCharacter;

//var myFindChangeFile = myFindFile(“/FindChangeSupport/FindChangeList.txt”)

if(myFindChangeFile != null){

myFindChangeFile = File(myFindChangeFile);

var myResult = myFindChangeFile.open(“r”, undefined, undefined);

if(myResult == true){

//Loop through the find/change operations.

do{

myLine = myFindChangeFile.readln();

//Ignore comment lines and blank lines.

if((myLine.substring(0,4)==”text”)||(myLine.substring(0,4)==”grep”)||(myLine.substring(0,5)==”glyph”)){

myFindChangeArray = myLine.split(“t”);

//The first field in the line is the findType string.

myFindType = myFindChangeArray[0];

//The second field in the line is the FindPreferences string.

myFindPreferences = myFindChangeArray[1];

//The second field in the line is the ChangePreferences string.

myChangePreferences = myFindChangeArray[2];

//The fourth field is the range–used only by text find/change.

myFindChangeOptions = myFindChangeArray[3];

switch(myFindType){

case “text”:

myFindText(myObject, myFindPreferences, myChangePreferences, myFindChangeOptions);

break;

case “grep”:

myFindGrep(myObject, myFindPreferences, myChangePreferences, myFindChangeOptions);

break;

case “glyph”:

myFindGlyph(myObject, myFindPreferences, myChangePreferences, myFindChangeOptions);

break;

}

}

} while(myFindChangeFile.eof == false);

myFindChangeFile.close();

}

}

}

function myFindText(myObject, myFindPreferences, myChangePreferences, myFindChangeOptions){

//Reset the find/change preferences before each search.

app.changeTextPreferences = NothingEnum.nothing;

app.findTextPreferences = NothingEnum.nothing;

var myString = “app.findTextPreferences.properties = “+ myFindPreferences + “;”;

myString += “app.changeTextPreferences.properties = ” + myChangePreferences + “;”;

myString += “app.findChangeTextOptions.properties = ” + myFindChangeOptions + “;”;

app.doScript(myString, ScriptLanguage.javascript);

myFoundItems = myObject.changeText();

//Reset the find/change preferences after each search.

app.changeTextPreferences = NothingEnum.nothing;

app.findTextPreferences = NothingEnum.nothing;

}

function myFindGrep(myObject, myFindPreferences, myChangePreferences, myFindChangeOptions){

//Reset the find/change grep preferences before each search.

app.changeGrepPreferences = NothingEnum.nothing;

app.findGrepPreferences = NothingEnum.nothing;

var myString = “app.findGrepPreferences.properties = “+ myFindPreferences + “;”;

myString += “app.changeGrepPreferences.properties = ” + myChangePreferences + “;”;

myString += “app.findChangeGrepOptions.properties = ” + myFindChangeOptions + “;”;

app.doScript(myString, ScriptLanguage.javascript);

var myFoundItems = myObject.changeGrep();

//Reset the find/change grep preferences after each search.

app.changeGrepPreferences = NothingEnum.nothing;

app.findGrepPreferences = NothingEnum.nothing;

}

function myFindGlyph(myObject, myFindPreferences, myChangePreferences, myFindChangeOptions){

//Reset the find/change glyph preferences before each search.

app.changeGlyphPreferences = NothingEnum.nothing;

app.findGlyphPreferences = NothingEnum.nothing;

var myString = “app.findGlyphPreferences.properties = “+ myFindPreferences + “;”;

myString += “app.changeGlyphPreferences.properties = ” + myChangePreferences + “;”;

myString += “app.findChangeGlyphOptions.properties = ” + myFindChangeOptions + “;”;

app.doScript(myString, ScriptLanguage.javascript);

var myFoundItems = myObject.changeGlyph();

//Reset the find/change glyph preferences after each search.

app.changeGlyphPreferences = NothingEnum.nothing;

app.findGlyphPreferences = NothingEnum.nothing;

}

function myFindFile(myFilePath){

var myScriptFile = myGetScriptPath();

var myScriptFile = File(myScriptFile);

var myScriptFolder = myScriptFile.path;

myFilePath = myScriptFolder + myFilePath;

if(File(myFilePath).exists == false){

//Display a dialog.

myFilePath = File.openDialog(“Choose the file containing your find/change list”);

}

return myFilePath;

}

function myGetScriptPath(){

try{

myFile = app.activeScript;

}

catch(myError){

myFile = myError.fileName;

}

return myFile;

}

I changed the code a bit and it now works on multi files: