Write a function for encoding USPS Intelligent Mail Barcodes (IMBs)

function encode(barcode){
  let string = barcode.toString();
  let barcodeArray = string.split("");
  let encodedArray = []
  let sum = 0;
  let checksum = 0;
  let sumOfCheck = 0;
  let finalCheck = 0;
  let encodedCheck = 0;
  let finalBarcode = "";
  let unencodedBarcode = "";
  let encodedBarcode = "";
  let arrCheck = 0;
  let codeArr = ["||:::", ":::||", "::|:|", "::||:", ":|::|", ":|:|:", ":||::", "|:::|", "|::|:", "|:|::"]

  if(barcode.length != 5){
    return "Please enter a 5 digit barcode"
  }
  
  for(let i = 0; i < barcodeArray.length; i++){
    sum += parseInt(barcodeArray[i])
    unencoded