How to convert the text array to the following format?

if there is an array

["1","2","3"]

how to convert to

"1","2","3"
Aug.06,2021

arr.join(",")

still keep quotation marks

let arr = ["1","2","3"]
let str = JSON.stringify(arr)
str = str.substring(1, str.length - 1)

'1','2','3'

what is this?

if you want to convert the string
visually, it should be
'Test 1, Test 2, Test 3'


arr.toString()  
arr.join() //','
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