How to retain javascript array while page refresh?

Question

PHP file

<input type="text" id="txtMyText">
<button type="button" id="myButton" onclick="addItemToArray()">Add to Array</button>

Javascript file

var myArray = []

function addItemToArray()
{
    myArray.push(document.getElementById("txtMyText").value);
}

Whenever I enter some value in a text field and hit the button, value gets stored in the array. When a page is refreshed, my array becomes empty. I want to retain its elements until I remove them manually. How do I retain them? Should I put array in PHP session or hidden field? If yes, then how?

Answer 1

Use localStorage API for this purpose, Use setItem() method and do stringify the array before storing into the localStorage . You can retrieve the stored item by getItem() and parse the stored array using JSON.parse() , something like

if(localStorage.getItem('textValues') == null){
    var myArray =[];
}else{
    myArray =  JSON.parse(localStorage.getItem('textValues'));
   //-----------^parse the item by getting---^--stored item
}

function addItemToArray(){
    myArray.push(document.getElementById("txtMyText").value);
    localStorage.setItem('textValues', JSON.stringify(myArray));
    //------------^store the item by stringify--^
}

DEMO

Answer 2

You could use the browser's internal storage: https://developer.mozilla.org/en-US/docs/Web/Guide/API/DOM/Storage

Store the array:

sessionStorage.setItem("items", JSON.stringify(items));

Get the array from storage:

var items = JSON.parse(sessionStorage.getItem("items"));

Answer 3

To retain it on refresh you are going to need to store in local storage. localStorage.setItem("storageName", myArray) then to retrieve it localStorage.getItem("storageName") or var myArray = localStorage.getItem("storageName")

Answer 4

probably the easiest way would be using jQuery cookie

edit var myArray = [] /edit

if ($.cookie('arrayItems')){
      myArray=JSON.parse($.cookie('arrayItems'));
}


 function addItemToArray()  
 {
   myArray.push(document.getElementById("txtMyText").value);
  $.cookie('arrayItems',JSON.stringify(myArray));
 }

Answer 5

If you want to use a PHP session, I would take advantage of AJAX. You'll need to create a file to handle the array as you create it. Here's a simple example.

Your first page

<?php 
    //start the PHP session to save your array in
    session_start(); 
?>

<script type="text/javascript">
var myArray = [];
<?php
    if(isset($_SESSION['myArray'])) {
        foreach($_SESSION['myArray'] as $item){
            // prepopulate the session array from PHP
            echo "myArray[] = ".$item.";";
        }
    }
?>
function addItemToArray(){
    var addvalue = document.getElementById("txtMyText").value;
    myArray.push(addvalue);
    if (window.XMLHttpRequest){  var xmlhttp=new XMLHttpRequest();  }else {  var xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");  }
    xmlhttp.onreadystatechange=function()  {
      if (xmlhttp.readyState==4 && xmlhttp.status==200)    {
            document.getElementById("myDiv").innerHTML += xmlhttp.responseText .", ";
        }
    }
    xmlhttp.open("GET","save_array.php?newValue="+,true);
    xmlhttp.send();
}
</script>

<div id="show_my_array">
    <?php
        //show array saved from last time
        if(isset($_SESSION['myArray'])) {
            foreach($_SESSION['myArray'] as $item){
                // prepopulate the session array from PHP
                echo $item.", ";
            }
        }
    ?>
</div>
<input type="text" id="txtMyText">
<button type="button" id="myButton" onclick="addItemToArray()">Add to Array</button>

save_array.php

<?php
session_start();
if(!isset($_SESSION['myArray'])){
    $_SESSION['myArray'] = array();
}
$_SESSION['myarray'][] = $_GET['newValue'];
echo $_GET['newValue'];
?>