How to pass Array from Javascript to PHP - php

Question

I have a function which saves an array each time the button is clicked to localStorage.The button will be clicked multiple times and I need to put this Array list into PHP somehow which is on another page from this file.
Thanks
a.js
(this function listens onLoad of the page)
function doFirst(){
var button = document.getElementById("button");
button.addEventListener("click", save, false);
var buttons = document.getElementById("clear");
buttons.addEventListener("click", clear, false);
var buttonss = document.getElementById("submittodb");
buttonss.addEventListener("click", toPHP, false);
$.ajax({
method: 'post',
dataType: 'json',
url: 'edit.php',
data: { items: oldItems }, //NOTE THIS LINE, it's QUITE important
success: function() {//some code to handle successful upload, if needed
}
});
}
function save(){
var oldItems = JSON.parse(localStorage.getItem('itemsArray')) || [];
var newItem = {
'num': document.getElementById("num").value,
'methv': document.getElementById("methv").value,
'q1': document.getElementById("q1").value,
'q2':document.getElementById("q2").value,
'q3':document.getElementById("q3").value,
'q4':document.getElementById("q4").value,
'comm':document.getElementById("comm").value,
};
oldItems.push(newItem);
localStorage.setItem('itemsArray', JSON.stringify(oldItems));}
edit.php
$parsed_array = json_decode($_POST['items']);
and i get the error: Notice: Undefined index: items in /home/project/edit.php on line 9

Answer 1

In order to pass this array to PHP you need to:
JSon-encode it
Make an AJAX or POST request to PHP
Parse the passed array into PHP array
If you're using jQuery (if you're not you should start - it is really handy tool) steps (1) and (2) is as simple as
$.ajax({
method: 'post',
dataType: 'json',
url: 'the URL of PHP page that will handle the request',
data: { items: oldItems }, //NOTE THIS LINE, it's QUITE important
success: function() {//some code to handle successful upload, if needed
}
});
In PHP you can parse the passed array with just
$parsed_array = json_decode($_POST['items']);
There is a direct connection between { items: oldItems } and $_POST['items']. The name of variable you give to the parameter in javascript call will be the name of key in $_POST array where it ends up. So if you just use data: oldItems in javascript you'll have all your entities scattered around the $_POST array.
More on $.ajax, and json_decode for reference.

Answer 2

You can create an AJAX function (use jQuery) and send the JSON data to the server and then manage it using a PHP function/method.
Basically, you need to send the data from the client (browser) back to the server where the database hosted.

Answer 3

Call JSON.stringify(oldItems); to create the json string
Do a Do a POST request using AJAX.
Probably the simplest way is using jQuery:
$.post('http://server.com/url.php', { items: JSON.stringify(oldItems) }, function(response) {
// it worked.
});