App Script Google Docs Replace Text in Body - google-apps-script

Question

I'm having trouble, replacing text in a Google Doc, using App Script.
Inside the document I have certain tags/tokens like ${TOKEN.SUBTOKEN}. I get the document as text and extract all the TOKEN's as a list with a Regex without issue, but when I want to use the replaceText function, I have issues. When I execute the replaceText line, it doesn't change the value in the document, but returns an element from the document. I can't find a way to replace the text I'm targeting.
var doc = DocumentApp.openById(docId);
var docBody = doc.getBody();
// tokenValues is the Object that contains the values to replace.
var fields = docBody.getText().match(/\$\{[a-z0-9\.\_]+\}/gi);
for (var i = 0; i < fields.length; i++ ) {
fields[i] = fields[i].substring(2, fields[i].length-1);
}
for (var i; i < fields.length; i++) {
Logger.log(docBody.replaceText(new RegExp('\\${ *' + fields[i].replace('/\./g', '\.') + '\ *}', tokenValues[i]));
}
How should I approach this, I'm having trouble with It because the documentation is not that explicit, (or maybe I don't understand it)

Answer 1

I did something similar to your question.
Here's the text:
{{ClientName}} would like to have a {{Product}} {{done/created}}. The purpose of this {{Product}} is to {{ProductPurpose}}. We have experience with such testing and development, and will develop and test the {{Product}} for {{ClientName}}.
Here's the code:
function searchReplace(){
var regex1=new RegExp('{{([a-zA-Z/]+)}}','g');
var tA=[];
var srchA=[];
var fldA=[];
var s=DocumentApp.getActiveDocument().getBody().getText();
while((tA=regex1.exec(s))!==null){//get all fields
fldA.push(tA[1]);
}
for(var i=0;i<fldA.length;i++){//Get unique fields
if(srchA.indexOf(fldA[i])==-1){
srchA.push(fldA[i]);
}
}
var doc=DocumentApp.getActiveDocument();
var body=doc.getBody();
for(var i=0;i<srchA.length;i++){
var searchPattern=Utilities.formatString('\\{\\{(%s)\\}\\}', srchA[i]);//need double backslashes here.
var prompt=Utilities.formatString('Enter Replacement for %s',srchA[i]);
var resp=DocumentApp.getUi().prompt('Replacement Text',prompt , DocumentApp.getUi().ButtonSet.OK_CANCEL)
if(resp.getSelectedButton()==DocumentApp.getUi().Button.OK){
body.replaceText(searchPattern, resp.getResponseText());//replaces all instances of the field
}
}
}