How can I keep an array filled outside of a function? - google-apps-script

Question

This question is part of finding a solution to a larger problem. However, I am wondering if there is a way to use a function to fill an Array. Based on the test code below, it seems arrays automatically empty after the function. I am looking to have a function that fills the array repeatedly, and another one that triggers to paste the resulting array.Note the paintArray=[] defined outside of the functions.
The console logs '1' for fillArray() but when I run logArray() right after it logs [].
const paintArray = []
function logArray(){
console.log(paintArray)
}
function fillArray(){
paintArray.push(1)
console.log(paintArray)
}

Answer 1

You can use Properties Service this way:
var scriptProp = PropertiesService.getScriptProperties();
function logArray(){
Logger.log(scriptProp.getProperty("paintArray"))
}
function fillArray(){
var obj = scriptProp.getProperty("paintArray")
if(obj){ //check if paintArray Object exists
var arr = JSON.parse(obj); //parse the value to array
arr.push(1); //push value 1
scriptProp.setProperty("paintArray", JSON.stringify(arr)) //set new value of arr to properties
}else{
scriptProp.setProperty("paintArray", "[1]"); //set initial value if paintArray object is undefined
}
}
First run:
Second run:
Third run:

Answer 2

Save and Retrieve Array from Properties Service
function saveArray(a) {
PropertiesService.getScriptProperties().setProperty("myarray",JSON.stringify(a));
}
function getArray() {
return JSON.parse(PropertiesService.getScriptProperties().getProperty("myarray"));
}