How to use Universal Find and Replace? (ELI5) - google-apps-script

Question

I'm working on a project in a shared Google Drive folder where we recently learned we need to change some strings, that are found in all the documents, with slightly different strings. There are hundreds of files, and it'd be impossible to go through them all one by one, and after some looking I found a Universal Find and Replace script.
https://ctrlq.org/code/19926-universal-find-replace-in-google-drive
Problem is, I have little to no experience with code and even with the instructions given on the site, I have no clue what I have to do with the script. All of it is gibberish to me, and I'd be unbelievably grateful if someone could walk me through all of it.
Questions:
Where in the script do I specify the Drive folder in question and how do I specify it? The "folder path" thing has me even more confused, so if you can let me know where exactly I can find the needed info, that would be great.
Where do I specify the strings I need to replace? I can obviously tell that doc.replaceText has something to do with it, but the fact that it says "You can use regex too" makes me curious if there's anything else I need to change before that?
How should I make a copy of the script code and where in my Google Drive do I place the file?
If there's any other steps I might be overlooking, please mention those as well.
Also, will it be possible to replace more than one string in a single script? (i.e change all "red" to "blue" and change all "black" to "white")
Thank you all in advance, this might end up being a lifesaver?

Answer 1

You might want to look at Apps Script's Drive Service and Document Service to help you be more familiar about the classes and functions to be used.
Drive Service
This service allows scripts to create, find, and modify files and folders in Google Drive.
Document Service
This service allows scripts to create, access, and modify Google Docs files.
Creating a Folder
Using the sample code :
// Log the name of every folder in the user's Drive.
var folders = DriveApp.getFolders();
while (folders.hasNext()) {
var folder = folders.next();
Logger.log(folder.getName());
}
You can set
var newFolder = DriveApp.createFolder('My New Folder');
//To check if you successfully created a folder
Logger.log(newFolder.getId())
//To set sub folder under "My New Folder"
var id = newFolder.getId()
var subFolder = newFolder.createFolder('New Sub Folder')
2. Where do I specify the strings I need to replace? I can obviously tell that doc.replaceText has something to do with it, but the fact that it says "You can use regex too" makes me curious if there's anything else I need to change before that?
You can use findText(searchPattern, from)
Searches the contents of the element for the specified text pattern, starting from a given search result.
A subset of the JavaScript regular expression features are not fully supported, such as capture groups and mode modifiers.
The provided regular expression pattern is independently matched against each text block contained in the current element.
3. How should I make a copy of the script code and where in my Google Drive do I place the file?
You can use Apps Script Console to create your codes, this will be placed in you drive folder.
Lastly, here is a sample code that will change the color of the text:
var body = DocumentApp.getActiveDocument().getBody();
// Use editAsText to obtain a single text element containing
// all the characters in the document.
var text = body.editAsText();
// Insert text at the beginning of the document.
text.insertText(0, 'Inserted text.\n');
// Insert text at the end of the document.
text.appendText('\nAppended text.');
// Make the first half of the document blue.
text.setForegroundColor(0, text.getText().length / 2, '#00FFFF');
Hope it helps!