# [name]

Handles and keeps track of loaded and pending data. A default global instance of this class is created and used by loaders if not supplied manually - see [page:DefaultLoadingManager].
In general that should be sufficient, however there are times when it can be useful to have separate loaders - for example if you want to show separate loading bars for objects and textures.

## Code Example

This example shows how to use LoadingManager to track the progress of [page:OBJLoader].

`const manager = new THREE.LoadingManager(); manager.onStart = function ( url, itemsLoaded, itemsTotal ) { console.log( 'Started loading file: ' + url + '.\nLoaded ' + itemsLoaded + ' of ' + itemsTotal + ' files.' ); }; manager.onLoad = function ( ) { console.log( 'Loading complete!'); }; manager.onProgress = function ( url, itemsLoaded, itemsTotal ) { console.log( 'Loading file: ' + url + '.\nLoaded ' + itemsLoaded + ' of ' + itemsTotal + ' files.' ); }; manager.onError = function ( url ) { console.log( 'There was an error loading ' + url ); }; const loader = new THREE.OBJLoader( manager ); loader.load( 'file.obj', function ( object ) { // } );`

In addition to observing progress, a LoadingManager can be used to override resource URLs during loading. This may be helpful for assets coming from drag-and-drop events, WebSockets, WebRTC, or other APIs. An example showing how to load an in-memory model using Blob URLs is below.

`// Blob or File objects created when dragging files into the webpage. const blobs = {'fish.gltf': blob1, 'diffuse.png': blob2, 'normal.png': blob3}; const manager = new THREE.LoadingManager(); // Initialize loading manager with URL callback. const objectURLs = []; manager.setURLModifier( ( url ) => { url = URL.createObjectURL( blobs[ url ] ); objectURLs.push( url ); return url; } ); // Load as usual, then revoke the blob URLs. const loader = new THREE.GLTFLoader( manager ); loader.load( 'fish.gltf', (gltf) => { scene.add( gltf.scene ); objectURLs.forEach( ( url ) => URL.revokeObjectURL( url ) ); });`

## Examples

[example:webgl_loader_obj WebGL / loader / obj]
[example:webgl_postprocessing_outline WebGL / postprocessing / outline]

## Constructor

### [name]( [param:Function onLoad], [param:Function onProgress], [param:Function onError] )

[page:Function onLoad] — (optional) this function will be called when all loaders are done.
[page:Function onProgress] — (optional) this function will be called when an item is complete.
[page:Function onError] — (optional) this function will be called a loader encounters errors.
Creates a new [name].

## Properties

### [property:Function onStart]

This function will be called when loading starts. The arguments are:
[page:String url] — The url of the item just loaded.
[page:Integer itemsLoaded] — the number of items already loaded so far.
[page:Integer itemsTotal] — the total amount of items to be loaded.
By default this is undefined.

### [property:Function onLoad]

This function will be called when all loading is completed. By default this is undefined, unless passed in the constructor.

### [property:Function onProgress]

This function will be called when an item is complete. The arguments are:
[page:String url] — The url of the item just loaded.
[page:Integer itemsLoaded] — the number of items already loaded so far.
[page:Integer itemsTotal] — the total amount of items to be loaded.
By default this is undefined, unless passed in the constructor.

### [property:Function onError]

This function will be called when any item errors, with the argument:
[page:String url] — The url of the item that errored.
By default this is undefined, unless passed in the constructor.

## Methods

### [method:this addHandler]( [param:Object regex], [param:Loader loader] )

[page:Object regex] — A regular expression.
[page:Loader loader] — The loader.

Registers a loader with the given regular expression. Can be used to define what loader should be used in order to load specific files. A typical use case is to overwrite the default loader for textures.

`// add handler for TGA textures manager.addHandler( /\.tga$/i, new TGALoader() );`

### [method:Loader getHandler]( [param:String file] )

[page:String file] — The file path.

Can be used to retrieve the registered loader for the given file path.

### [method:this removeHandler]( [param:Object regex] )

[page:Object regex] — A regular expression.

Removes the loader for the given regular expression.

### [method:String resolveURL]( [param:String url] )

[page:String url] — the url to load
Given a URL, uses the URL modifier callback (if any) and returns a resolved URL. If no URL modifier is set, returns the original URL.

### [method:this setURLModifier]( [param:Function callback] )

[page:Function callback] — URL modifier callback. Called with [page:String url] argument, and must return [page:String resolvedURL].
If provided, the callback will be passed each resource URL before a request is sent. The callback may return the original URL, or a new URL to override loading behavior. This behavior can be used to load assets from .ZIP files, drag-and-drop APIs, and Data URIs.

Note: The following methods are designed to be called internally by loaders. You shouldn't call them directly.

### [method:undefined itemStart]( [param:String url] )

[page:String url] — the url to load
This should be called by any loader using the manager when the loader starts loading an url.

### [method:undefined itemEnd]( [param:String url] )

[page:String url] — the loaded url
This should be called by any loader using the manager when the loader ended loading an url.

### [method:undefined itemError]( [param:String url] )

[page:String url] — the loaded url
This should be called by any loader using the manager when the loader errors loading an url.

## Source

[link:https://github.com/mrdoob/three.js/blob/master/src/loaders/LoadingManager.js src/loaders/LoadingManager.js]