Compare cell to an array and return a value in App script

Question

i am trying to create an app script to compare a cell value to an array, where column D has values (task1, task2... task6), each task has a level 1 or 2, therefore if column D2 has value "task1" then it is L1 and the value is set in the respective row in column O, it seems that I might have made several errors in the way as i am not getting the result i would like, any help would be much appreciated.

function fillValues() {
var spreadsheet = SpreadsheetApp.openById().getSheetByName()
var task = spreadsheet.getRange("D2:D" + spreadsheet.getLastRow())
var taskLevel = spreadsheet.getRange("O2:O" + spreadsheet.getLastRow())
var newRange = []
var newFillValue

task.getValues().map(function(value) {

var L1Tasks = ["task1", "task2", "task3"];
var L2Tasks = ["task4","task5", "task6"];
for (var i = 0; i < L1Tasks.length; i++){ 
if (value[0]==L1Tasks[i]) { 
newFillValue="L1" 
newRange.push([newFillValue]) }
else { newFillValue="L2" newRange.push([newFillValue]) } 
} 
}) 
taskLevel.setValues(newRange) 
}