Worker Demo

There is one table test that you can query. That table has the following fields:

You can do things like: select * from test, or insert into test (name) value ('something') or delete from test where id=10

You can add only 20 records and then the earliest records are deleted.

Enter a SQL statement:


// BLP 2023-02-26 - use new approach
// Demonstrates the use of a worker using AJAX calls.
// This is the main program for worker.main.php it uses
// worker.worker.js and worker.ajax.php
// See worker.ajax.php for a description of the 'test' table in the database 'test'.
// Load info from mysitemap.json for use by my framework SiteClass.
// Check SiteClass out at https://github.com/bartonlp/site-class.
// It has full documentation at that site.
// The worker.ajax.php uses the 'test' user and database.

$_site = require_once(getenv("SITELOADNAME"));
$S = new SiteClass($_site); // $S gives access to my framework.

// escapeltgt() is a little utility that change < and > to < >

$main = escapeltgt(file_get_contents("worker.main.php"));
$worker = escapeltgt(file_get_contents("worker.worker.js"));
$ajax = escapeltgt(file_get_contents("worker.ajax.php"));

$S->title = "Workers";
$S->banner = "<h1>Worker Demo</h1>";
$S->extra =<<<EOF
<!--<script src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.js"></script>-->
<script src="https://bartonphillips.net/js/syntaxhighlighter.js"></script>
<link rel='stylesheet' href="https://bartonphillips.net/css/theme.css">

jQuery(document).ready(function($) {
  var w1 = new Worker("worker.worker.js");

  w1.addEventListener("message", function(evt) {
    console.log("data: ", evt.data);
    if(Object.keys(evt.data)[0] == "ERROR" || Object.keys(evt.data)[0] == "DONE") {
    } else {
      var string = String.fromCharCode.apply(null, evt.data)
      //var string = new TextDecoder("utf-8").decode(evt.data);
      console.log("Main string: ", string);

  // now transfer array buffer

  const send = function(txt) {
    // use a map to create ascii to int.
    bufView = Uint8Array.from(txt, x => x.charCodeAt());
    console.log("Main bufView: ", bufView);
    w1.postMessage(bufView, [bufView.buffer]);

  $("#click").click(function() {
    var sql = $("input").val();
    return false;
  $("#clear").click(function() {
    return false;
  $("#showfiles").click(function() {
    return false;
$S->css =<<<EOF
input {
  width: 100%;
  font-size: 1rem;
button {
  cursor: pointer;
  font-size: 1rem;
#files {
  display: none;

// Use my framework to get the $top of the page which includes the <head> section
// the <body> tag and my banner which is in <header>.

[$top, $footer] = $S->getPageTopBottom();

// Render the page

echo <<<EOF
<p>There is one table <b>test</b> that you can query.
That table has the following fields:</p>
<li><i>id</i> which is an auto incrementing value.</li>
<li><i>name</i> which is an ascii field.</li>
<li><i>lasttime</i> which is an automatic time stamp.</li>
<p>You can do things like: <i>select * from test</i>, or
<i>insert into test (name) value ('something')</i> or
<i>delete from test where id=10</i></p>
<p>You can add only 20 records and then the earliest records are deleted.</p>
Enter a SQL statement: <input type="text" autofocus ><br>
<button id="click">Click Me</button>
<button id="clear">Clear</button>
<button id="showfiles">View the file
<b>worker.main.php</b>,<b>worker.worker.js</b> and <b>worker.ajax.php</b></button>
<div id="files">
<pre class='brush: php'>
<pre class='brush: js'>
<pre class='brush: php'>


// worker.worker.js This is javascript.
// This is the worker side of worker.main.php and it calls
// worker.ajax.php for the info from the 'test' table.
// See worker.ajax.php for description of the 'test' table in database
// 'test'.

// Add an event listener for 'message'. The data is in evt.data and we
// make it into a string and then pass the string to sendText()

addEventListener("message", function(evt) {
  var string = new TextDecoder("utf-8").decode(evt.data);
  console.log("Worker string: ", string);

// SendText() does the usual XMLHttpRequest() stuff to post to
// worker.ajax.php.

function sendText(txt) {
  // Use fetch() to send and receive the data.
  let ret = fetch("worker.ajax.php", {
    body: txt, // This is just plain sql
    method: "POST",
    headers: {
      'content-type': 'application/x-www-form-urlencoded'
  }).then(res => res.json()); // Get the json data
  ret.then(newtxt => {
    console.log("Worker response", newtxt);

    if(Object.keys(newtxt) == "ERROR" || Object.keys(newtxt) == "DONE") {
    } else {
      // Take the items out of newtxt which is an array.

      var rows = '';

      for(item of newtxt) {
        // Now the stuff in the array is an object so get the key and
        // value and put them into the rows variable.

        for([key, value] of Object.entries(item)) {
          rows += key + ": " + value + "\n";
        rows += "\n";

      // Now we do the same thing we did above to make the Transfer
      // buffer

      bufView = Uint8Array.from(rows, x => x.charCodeAt());
      console.log("Worker bufView: ", bufView);
      postMessage(bufView, [bufView.buffer]);


// This is part of the worker group.
// This is the AJAX server that is called from worker.worker.js
// The trio is worker.main.php, worker.worker.js and worker.ajax.php
  `name` varchar(254) DEFAULT NULL,
  PRIMARY KEY (`id`)

This table is in database "test" on bartonphillips.com.
The database allows only 'select, update, insert and delete' and the code below maintains a max of 20 entries.
The standard mysitemap.json has my normal database stuff. We change it here to ues the 'test'
user and the 'test' database which has the 'test' table.

$_site = require_once(getenv("SITELOADNAME"));

$_site->dbinfo->user = "test"; // use test user
$_site->dbinfo->database = "test"; // and test database

$S = new Database($_site);

// We are using fetch() in worker.worker.js so we need to get the data from 'php://input'

$sql = file_get_contents("php://input");

if(empty($sql)) {
  echo json_encode(["ERROR"=>"No sql statment"]);

// We could be passed something is will not work

try {
  if(preg_match("/insert/i", $sql)) {
    // We want to restrict the size of this table so check the TABLE_ROWS

    $S->query("select count(*) from test");

    $cnt = $S->fetchrow('num')[0];
    $nn = $cnt - 19; // This is the number to delete

    if($cnt > 20) {
      $n = $S->query("delete from test order by id asc limit $nn"); // leave most resent 20
      $del = "Deleted $n items";

  $n = $S->query($sql);

  if(preg_match("/update|insert|delete/", $sql)) {
    echo json_encode(["DONE"=>"$del Rows Affected: $n"]);

  $rows = array();

  while($row = $S->fetchrow('assoc')) {
    $rows[] = $row;

  if(!count($rows)) {
    echo json_encode(["ERROR"=>"NO DATA"]);

  echo json_encode($rows); // encode the data and send it.
} catch(Exception $e) {
  echo json_encode(["ERROR"=> $e->getMessage()]);

echo "ERROR: GO AWAY<br>";