How to put timestamps within array in local storage?

Question

Hello I am creating an chrome extension and I am trying to put all my timestamps that a retrieved after visiting a url into an array in local storage but I am having trouble doing so. It continues to update timestamps and i want all my timestamps to stay the same. However it doesnt seem to save anything and i keep receiving this error. Do anyone know how to fix this error or what may be causing it.

function addRow() {
            
            
    
    const bg = chrome.extension.getBackgroundPage()    
    Object.keys(bg.get).forEach(function (url) {
    
    
        // Append product to the table
            var data = [];
            data = JSON.parse(localStorage.getItem('session')) || [];
            // Push the new data (whether it be an object or anything else) onto the array
            data.push( Date.now() );
            localStorage.setItem('session', JSON.stringify(data));
            myDate = data;
        
            //protocol
            var arr = url.split("/");
            var protocoll = arr[0] + "//" + arr[2];
        
            //inputed data --
            browser= "Google Chrome"; 
            protocol = protocoll;
            downloads = "example";
            description = "example";
            //use data or myDate as time
            time = myDate;
            
                
        
        //will put dates in array and replace it and have var as myDate
    // add new row to the table
                  //1 = in the top 
                  //table.rows.length = the end
                  //table.rows.length/2+1 = the center 

            var newRow = table.insertRow(0);
            
            //console.log(table.rows.length) gives length of table
                  
                  // add cells to the row
                  var browserCell = newRow.insertCell(0);
                  var timeCell = newRow.insertCell(1);
                  var urlCell = newRow.insertCell(2);
                  var protocolCell = newRow.insertCell(3);
                  var downloadsCell = newRow.insertCell(4);
                  var descCell = newRow.insertCell(5);
                  
                  // add the data to the cells
                  
                  urlCell.innerHTML = `${url}`; 
                  timeCell.innerHTML = time;
                    browserCell.innerHTML = browser;
                    descCell.innerHTML = description;
                    protocolCell.innerHTML = protocol;
                    downloadsCell.innerHTML = downloads;
                  console.log("add row works");
     }) 
            }
 

Answer 1

"Unexpected token u at position 0" means that you're trying to parse an undefined. Replace

var data = [];
data = JSON.parse(localStorage.getItem('session')) || [];

with

var data = JSON.parse(localStorage.getItem('session') || "[]");

Answer 2

There is a bug in the code.

data = JSON.parse(localStorage.getItem('session')) || [];

should be:

data = JSON.parse(localStorage?.getItem('session') ?? []);