Phaser API Documentation

pack(key, [url], [dataKey], [xhrSettings])


Adds a JSON File Pack, or array of packs, to the current load queue.

You can call this method from within your Scene's preload, along with any other files you wish to load:

function preload ()
    this.load.pack('level1', 'data/Level1Files.json');

A File Pack is a JSON file (or object) that contains details about other files that should be added into the Loader. Here is a small example:

   "test1": {
       "files": [
               "type": "image",
               "key": "taikodrummaster",
               "url": "assets/pics/taikodrummaster.jpg"
               "type": "image",
               "key": "sukasuka-chtholly",
               "url": "assets/pics/sukasuka-chtholly.png"
   "meta": {
       "generated": "1401380327373",
       "app": "Phaser 3 Asset Packer",
       "url": "[](",
       "version": "1.0",
       "copyright": "Photon Storm Ltd. 2018"

The pack can be split into sections. In the example above you'll see a section called test1. You can tell the load.pack` method to parse only a particular section of a pack. The pack is stored in the JSON Cache, so you can pass it to the Loader to process additional sections as needed in your game, or you can just load them all at once without specifying anything.

The pack file can contain an entry for any type of file that Phaser can load. The object structures exactly match that of the file type configs, and all properties available within the file type configs can be used in the pack file too.

The file is not loaded right away. It is added to a queue ready to be loaded either when the loader starts, or if it's already running, when the next free load slot becomes available. This happens automatically if you are calling this from within the Scene's preload method, or a related callback. Because the file is queued it means you cannot use the file immediately after calling this method, but must wait for the file to complete. The typical flow for a Phaser Scene is that you load assets in the Scene's preload method and then when the Scene's create method is called you are guaranteed that all of those assets are ready for use and have been loaded.

If you call this from outside of preload then you are responsible for starting the Loader afterwards and monitoring its events to know when it's safe to use the asset. Please see the Phaser.Loader.LoaderPlugin class for more details.

The key must be a unique String. It is used to add the file to the global JSON Cache upon a successful load. The key should be unique both in terms of files being loaded and files already present in the JSON Cache. Loading a file using a key that is already taken will result in a warning. If you wish to replace an existing file then remove it from the JSON Cache first, before loading a new one.

Instead of passing arguments you can pass a configuration object, such as:

    key: 'level1',
    url: 'data/Level1Files.json'

See the documentation for Phaser.Types.Loader.FileTypes.PackFileConfig for more details.

If you have specified a prefix in the loader, via Loader.setPrefix then this value will be prepended to this files key. For example, if the prefix was LEVEL1. and the key was Waves the final key will be LEVEL1.Waves and this is what you would use to retrieve the text from the JSON Cache.

The URL can be relative or absolute. If the URL is relative the Loader.baseURL and Loader.path values will be prepended to it.

If the URL isn't specified the Loader will take the key and create a filename from that. For example if the key is "data" and no URL is given then the Loader will set the URL to be "data.json". It will always add .json as the extension, although this can be overridden if using an object instead of method arguments. If you do not desire this action then provide a URL.

You can also optionally provide a dataKey to use. This allows you to extract only a part of the JSON and store it in the Cache, rather than the whole file. For example, if your JSON data had a structure like this:

    "level1": {
        "baddies": {
            "aliens": {},
            "boss": {}
    "level2": {},
    "level3": {}

And you only wanted to store the boss data in the Cache, then you could pass level1.baddies.bossas the dataKey.

Note: The ability to load this type of file will only be available if the Pack File type has been built into Phaser. It is available in the default build but can be excluded from custom builds.


name type arguments description
key string | Phaser.Types.Loader.FileTypes.PackFileConfig | Array.<Phaser.Types.Loader.FileTypes.PackFileConfig>

The key to use for this file, or a file configuration object, or array of them.

url string <optional>

The absolute or relative URL to load this file from. If undefined or null it will be set to <key>.json, i.e. if key was "alien" then the URL will be "alien.json".

dataKey string <optional>

When the JSON file loads only this property will be stored in the Cache.

xhrSettings Phaser.Types.Loader.XHRSettingsObject <optional>

An XHR Settings configuration object. Used in replacement of the Loaders default XHR Settings.


The Loader instance.

Since: 3.7.0