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Dynamic Photo Gallery JSON Ajax PHP Tutorial

Published : November 17, 2014   •   Last Edited : November 24, 2025   •   Author : Adam Khoury
In this lesson we demonstrate how to build a very lightweight dynamic photo gallery using Ajax, PHP and JSON. json_gallery_data.php 
<?php
header("Content-Type: application/json");
$folder = $_POST["folder"];
$jsonData = '{';
$dir = $folder."/";
$dirHandle = opendir($dir); 
$i = 0;
while ($file = readdir($dirHandle)) {
	if(!is_dir($file) && strpos($file, '.jpg')){
		$i++;
		$src = "$dir$file";
$jsonData .= '"img'.$i.'":{ "num":"'.$i.'","src":"'.$src.'", "name":"'.$file.'" },';
    }
}
closedir($dirHandle);
$jsonData = chop($jsonData, ",");
$jsonData .= '}';
echo $jsonData;
?>
JSON_tutorial_5.html 
<!DOCTYPE html>
<html>
<head>
<style>
body { margin:0px; background:#000; color:#CCC; }
div#pagetop { position:fixed; background: #333; padding:20px; font-size:36px; width:100%; border-bottom:#000 1px solid; }
div#thumbnailbox { float:left; margin-top:82px; width:120px; background:#292929; }
div#thumbnailbox > div { width:100px; height:80px; overflow:hidden; margin:10px; cursor:pointer; }
div#thumbnailbox > div > img { width:100px; }
div#pictureframe { position:fixed; left:140px; top:100px; width:700px; height:500px; }
</style>
<script>
function ajax_json_gallery(folder){
	document.getElementById("pagetop").innerHTML = "Dynamic JSON Ajax PHP Driven Image Gallery";
	var thumbnailbox = document.getElementById("thumbnailbox");
	var pictureframe = document.getElementById("pictureframe");
    var hr = new XMLHttpRequest();
    hr.open("POST", "json_gallery_data.php", true);
    hr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    hr.onreadystatechange = function() {
	    if(hr.readyState == 4 && hr.status == 200) {
		    var d = JSON.parse(hr.responseText);
			pictureframe.innerHTML = "<img src='"+d.img1.src+"'>";
			thumbnailbox.innerHTML = "";
			for(var o in d){
				if(d[o].src){
				    thumbnailbox.innerHTML += '<div onclick="putinframe(\''+d[o].src+'\')"><img src="'+d[o].src+'"></div>';
				}
			}
	    }
    }
    hr.send("folder="+folder);
    thumbnailbox.innerHTML = "requesting...";
}
function putinframe(src){
	var pictureframe = document.getElementById("pictureframe");
	pictureframe.innerHTML = '<img src="'+src+'">';
}
</script>
</head>
<body>
<div id="pagetop"></div>
<div id="thumbnailbox"></div>
<div id="pictureframe"></div>
<script>ajax_json_gallery('gallery1');</script>
</body>
</html>
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