Update Day of the Week via Google Scripts - google-apps-script

Question

I've created the following code to run a manual script to change the day in multiple instances within a Google Slides presentation. If the day is Monday, the script changes it to Thursday. If it is Thursday, the other script changes it to Monday.
function futurebriefthurs() {
var currdate = new Date();
var daystochange = 3;
var newbriefday = new Date(currdate.getFullYear(), currdate.getMonth(), currdate.getDate() + daystochange);
var NextBrief = Utilities.formatDate(new Date(newbriefday), "GMT-7", "EEEEE");
var pattern = "\\b\\d{1,2}/\\d{1,2}/\\d{4}\\b";
var slides = SlidesApp.getActivePresentation().getSlides();
var slidesLength = slides.length;
for (var i = 0; i < slidesLength; i++) {
var shapes = slides[i].getShapes();
var shapesLength = shapes.length;
for (var j = 0; j < shapesLength; j++) {
if (shapes[j].getDescription() == "$NextBrief") {
var textRange = shapes[j].getText();
textRange.clear();
textRange.insertText(0, NextBrief);
}
}
}
}
function futurebriefmon() {
var currdate = new Date();
var daystochange = 4;
var newbriefday = new Date(currdate.getFullYear(), currdate.getMonth(), currdate.getDate() + daystochange);
var NextBrief = Utilities.formatDate(new Date(newbriefday), "GMT-7", "EEEEE");
var pattern = "\\b\\d{1,2}/\\d{1,2}/\\d{4}\\b";
var slides = SlidesApp.getActivePresentation().getSlides();
var slidesLength = slides.length;
for (var i = 0; i < slidesLength; i++) {
var shapes = slides[i].getShapes();
var shapesLength = shapes.length;
for (var j = 0; j < shapesLength; j++) {
if (shapes[j].getDescription() == "$NextBrief") {
var textRange = shapes[j].getText();
textRange.clear();
textRange.insertText(0, NextBrief);
}
}
}
}
What I would like to do is have a script that runs upon opening the presentation that checks the current day and makes the same changes automatically. We use this presentation on scheduled days so the need to change the day to other than Monday and Thursday is minimal.
At some point, I would like to be able to have the changed based on Google Calendar entries, but that is for another day. :-)

Answer 1

I think something like this will work.
You just need to run createOpenTrigger() when you install the code. I assumed everything else in the code was working.
function createOpenTrigger(){
var triggers=ScriptApp.getProjectTriggers();
var tA=[];
for(var i=0;i<triggers.length;i++){tA.push(triggers[i].getHandlerFunction());}
if(tA.indexOf('futureBrief')!=-1){
ScriptApp.newTrigger('futureBrief').forSpreadsheet(sheet).onOpen().create();
}
}
function futureBrief() {
var currdate = new Date();
var dtcA=[0,4,0,0,3,0,0];
var daystochange=dtcA[currdate.getDay()];
if(daystochange>0){
var newbriefday = new Date(currdate.getFullYear(), currdate.getMonth(), currdate.getDate() + daystochange);
var NextBrief = Utilities.formatDate(new Date(newbriefday), "GMT-7", "EEEEE");
var pattern = "\\b\\d{1,2}/\\d{1,2}/\\d{4}\\b";
var slides = SlidesApp.getActivePresentation().getSlides();
var slidesLength = slides.length;
for (var i = 0; i < slidesLength; i++) {
var shapes = slides[i].getShapes();
var shapesLength = shapes.length;
for (var j = 0; j < shapesLength; j++) {
if (shapes[j].getDescription() == "$NextBrief") {
var textRange = shapes[j].getText();
textRange.clear();
textRange.insertText(0, NextBrief);
}
}
}
}
}