Add missing load onProgress behaviour (#22990)

Load's onProgress function has an undocumented behaviour. If a server
does not set the Content-Length header, the onProgress function sets
total to 0. This change documents that behaviour.

docs/api/en/loaders/AnimationLoader.html

@@ -64,7 +64,7 @@
 		[page:String url] — the path or URL to the file. This can also be a
 			[link:https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs Data URI].<br />
 		[page:Function onLoad] — Will be called when load completes. The argument will be the loaded [page:AnimationClip animation clips].<br />
-		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — Will be called if load errors.<br /><br />
 
 		Begin loading from url and pass the loaded animation to onLoad.

docs/api/en/loaders/AudioLoader.html

@@ -81,7 +81,7 @@
 		[page:String url] — the path or URL to the file. This can also be a
 			[link:https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs Data URI].<br />
 		[page:Function onLoad] — Will be called when load completes. The argument will be the loaded text response.<br />
-		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — Will be called when load errors.<br />
 		</p>
 		<p>

docs/api/en/loaders/BufferGeometryLoader.html

@@ -73,7 +73,7 @@
 		[page:String url] — the path or URL to the file. This can also be a
 			[link:https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs Data URI].d<br />
 		[page:Function onLoad] — Will be called when load completes. The argument will be the loaded [page:BufferGeometry].<br />
-		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — Will be called when load errors.<br />
 		</p>
 		<p>

docs/api/en/loaders/CompressedTextureLoader.html

@@ -45,7 +45,7 @@
 		[page:String url] — the path or URL to the file. This can also be a
 			[link:https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs Data URI].<br />
 		[page:Function onLoad] — Will be called when load completes. The argument will be the loaded texture.<br />
-		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — Will be called when load errors.<br />
 		</p>
 		<p>

docs/api/en/loaders/CubeTextureLoader.html

@@ -64,7 +64,7 @@ scene.background = new THREE.CubeTextureLoader()
 		when looking up the positive-z axis -- in other words, using a left-handed coordinate system.
 		Since three.js uses a right-handed coordinate system, environment maps used in three.js will have pos-x and neg-x swapped.<br />
 		[page:Function onLoad] — Will be called when load completes. The argument will be the loaded [page:Texture texture].<br />
-		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — Will be called when load errors.<br />
 		</p>
 		<p>

docs/api/en/loaders/DataTextureLoader.html

@@ -45,7 +45,7 @@
 		[page:String url] — the path or URL to the file. This can also be a
 			[link:https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs Data URI].<br />
 		[page:Function onLoad] — Will be called when load completes. The argument will be the loaded texture.<br />
-		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — Will be called when load errors.<br />
 		</p>
 		<p>

docs/api/en/loaders/FileLoader.html

@@ -80,7 +80,7 @@
 				[link:https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs Data URI].<br />
 			[page:Function onLoad] (optional) — Will be called when loading completes. The argument will be the loaded response.<br />
 			[page:Function onProgress] (optional) — Will be called while load progresses. The argument will be the XMLHttpRequest instance,
-				which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+				which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 			[page:Function onError] (optional) — Will be called if an error occurs.<br /><br />
 
 			Load the URL and pass the response to the onLoad function.

docs/api/en/loaders/Loader.html

@@ -70,7 +70,7 @@
 		<h3>[method:Promise loadAsync]( [param:String url], [param:Function onProgress] )</h3>
 		<p>
 		[page:String url] — A string containing the path/URL of the file to be loaded.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		</p>
 		<p>
 		This method is equivalent to [page:.load], but returns a [link:https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise Promise].

docs/api/en/loaders/MaterialLoader.html

@@ -67,7 +67,7 @@
 		[page:String url] — the path or URL to the file. This can also be a
 			[link:https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs Data URI].<br />
 		[page:Function onLoad] — Will be called when load completes. The argument will be the loaded [page:Material].<br />
-		[page:Function onProgress] — Will be called while load progresses. The argument will be the progress event.<br />
+		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — Will be called when load errors.<br /><br />
 
 		Begin loading from url.

docs/api/en/loaders/ObjectLoader.html

@@ -77,7 +77,7 @@
 		[page:String url] — the path or URL to the file. This can also be a
 			[link:https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs Data URI].<br />
 		[page:Function onLoad] — Will be called when load completes. The argument will be the loaded [page:Object3D object].<br />
-		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — Will be called when load errors.<br />
 		</p>
 		<p>

docs/api/en/loaders/TextureLoader.html

@@ -85,7 +85,7 @@
 		[page:String url] — the path or URL to the file. This can also be a
 			[link:https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs Data URI].<br />
 		[page:Function onLoad] — Will be called when load completes. The argument will be the loaded [page:Texture texture].<br />
-		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — Will be called when load errors.<br /><br />
 
 		Begin loading from the given URL and pass the fully loaded [page:Texture texture] to onLoad. The method also returns a new texture object which can directly be used for material creation.

docs/examples/en/loaders/3DMLoader.html

@@ -165,7 +165,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.3dm</em> file.<br />
 		[page:Function onLoad] — A function to be called after the loading is successfully completed.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/BasisTextureLoader.html

@@ -95,7 +95,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.basis</em> file.<br />
 		[page:Function onLoad] — A function to be called after the loading is successfully completed.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/DRACOLoader.html

@@ -108,7 +108,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.drc</em> file.<br />
 		[page:Function onLoad] — A function to be called after the loading is successfully completed.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/FontLoader.html

@@ -71,7 +71,7 @@
 		[page:String url] — the path or URL to the file. This can also be a
 			[link:https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs Data URI].<br />
 		[page:Function onLoad] — Will be called when load completes. The argument will be the loaded font.<br />
-		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — Will be called when load errors.<br /><br />
 
 		Begin loading from url and pass the loaded [page:Texture texture] to onLoad.

docs/examples/en/loaders/GLTFLoader.html

@@ -194,7 +194,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.gltf</em> or <em>.glb</em> file.<br />
 		[page:Function onLoad] — A function to be called after the loading is successfully completed. The function receives the loaded JSON response returned from [page:Function parse].<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/KTX2Loader.html

@@ -85,7 +85,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.basis</em> file.<br />
 		[page:Function onLoad] — A function to be called after the loading is successfully completed.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/MMDLoader.html

@@ -75,7 +75,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.pmd</em> or <em>.pmx</em> file.<br />
 		[page:Function onLoad] — A function to be called after the loading is successfully completed.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, that contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/MTLLoader.html

@@ -36,7 +36,7 @@
 		<p>
 			[page:String url] — A string containing the path/URL of the <em>.mtl</em> file.<br />
 			[page:Function onLoad] — (optional) A function to be called after the loading is successfully completed. The function receives the loaded [page:MTLLoaderMaterialCreator MTLLoader.MaterialCreator] instance.<br />
-			[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes.<br />
+			[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 			[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives the error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/OBJLoader.html

@@ -74,7 +74,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.obj</em> file.<br />
 		[page:Function onLoad] — (optional) A function to be called after the loading is successfully completed. The function receives the loaded [page:Object3D] as an argument.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The function receives a XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The function receives a XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/PCDLoader.html

@@ -78,7 +78,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.pcd</em> file.<br />
 		[page:Function onLoad] — (optional) A function to be called after loading is successfully completed. The function receives loaded [page:Object3D] as an argument.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives the error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/PDBLoader.html

@@ -75,7 +75,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.pdb</em> file.<br />
 		[page:Function onLoad] — (optional) A function to be called after loading is successfully completed. The function receives the object having the following properties. [page:BufferGeometry geometryAtoms], [page:BufferGeometry geometryBonds] and the [page:Object JSON] structure.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives the error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/PRWMLoader.html

@@ -76,7 +76,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.prwm</em> file. Any <em>*</em> character in the URL will be automatically replaced by <em>le</em> or <em>be</em> depending on the platform endianness.<br />
 		[page:Function onLoad] — (optional) A function to be called after the loading is successfully completed. The function receives the loaded [page:BufferGeometry] as an argument.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The function receives a XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The function receives a XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/SVGLoader.html

@@ -97,7 +97,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.svg</em> file.<br />
 		[page:Function onLoad] — (optional) A function to be called after loading is successfully completed. The function receives an array of [page:ShapePath] as an argument.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, which contains [page:Integer total] and [page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives the error as an argument.<br />
 		</p>
 		<p>

docs/examples/en/loaders/TGALoader.html

@@ -76,7 +76,7 @@
 		<p>
 		[page:String url] — A string containing the path/URL of the <em>.tga</em> file. <br />
 		[page:Function onLoad] — (optional) A function to be called after loading is successfully completed. The function receives loaded [page:DataTexture] as an argument.<br />
-		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes.<br />
+		[page:Function onProgress] — (optional) A function to be called while the loading is in progress. The argument will be the XMLHttpRequest instance, which contains .[page:Integer total] and .[page:Integer loaded] bytes. If the server does not set the Content-Length header; .[page:Integer total] will be 0.<br />
 		[page:Function onError] — (optional) A function to be called if an error occurs during loading. The function receives the error as an argument.<br />
 		</p>
 		<p>