docs: remove stale sax-js references from README

README.md

@@ -32,7 +32,7 @@ imscJS bugs are tracked at https://github.com/sandflow/imscJS/issues.
 RUNTIME DEPENDENCIES
 ====================
 
-(required) [sax-js 1.2.1](https://www.npmjs.com/package/sax)
+imscJS requires an XML parser. By default it uses the browser's native [`DOMParser`](https://developer.mozilla.org/en-US/docs/Web/API/DOMParser), so no additional library is needed in a browser environment. In environments where `DOMParser` is not available, e.g. Node.js, the caller must provide `fromXML()` with a parser that implements the contract defined in [src/main/js/parser.js](src/main/js/parser.js), e.g. [sax-js](https://www.npmjs.com/package/sax).
 
 Rendering to HTML5 requires a browser environment, but parsing an IMSC document and transforming it into ISDs does not.
 
@@ -52,10 +52,9 @@ QUICK START
 
 * run the `build` target defined in [Gruntfile.cjs](./Gruntfile.cjs) using [grunt](http://gruntjs.com/).
 
-* the resulting `imsc.js` and `sax.js` files at `build/public_html/libs` are, respectively, the imscJS library and its sax-js dependency. For example, both libraries can be included in a web page as follows:
+* the resulting `imsc.js` file at `build/public_html/libs` is the imscJS library. For example, it can be included in a web page as follows:
 
 ```html
-    <script src="libs/sax.js"></script>
     <script src="libs/imsc.js"></script>
 ```
 
@@ -71,7 +70,7 @@ API
 
 imscJS renders an IMSC document in three distinct steps:
 
-* `fromXML(xmlstring, errorHandler, metadataHandler)` parses the document and returns a TT object. The latter contains opaque representation of the document and exposes the method `getMediaTimeEvents()` that returns a list of time offsets (in seconds) of the ISD, i.e. the points in time where the visual representation of the document change.
+* `fromXML(xmlstring, errorHandler, metadataHandler, parser)` parses the document and returns a TT object. The latter contains opaque representation of the document and exposes the method `getMediaTimeEvents()` that returns a list of time offsets (in seconds) of the ISD, i.e. the points in time where the visual representation of the document change. The optional `parser` argument allows the caller to provide an alternative XML parser, e.g. in environments where the browser's native `DOMParser` is not available.
 
 * `generateISD(tt, offset, errorHandler)` creates a canonical representation of the document (provided as a TT object generated by `fromXML()`) at a point in time (`offset` parameter). This point in time does not have to be one of the values returned by `getMediaTimeEvents()`. For example, given an ISOBMFF sample covering the interval `[a, b[`, `generateISD(tt, offset, errorHandler)` would be called first with `offset = a`, then in turn with offset set to each value of `getMediaTimeEvents()` that fall in the interval `]a, b[`.
 
@@ -104,12 +103,11 @@ BUILD
 imscJS is built using the `build:release` or `build:debug` Grunt tasks -- the `build` task is an alias of `build:debug`.
 
 The `dist` directory contains the following build artifacts:
-* `imsc.all.debug.js`: Non-minified build that includes the sax-js dependency.
-* `imsc.all.min.js`: Minified build that includes the sax-js dependency.
-* `imsc.debug.js`: Non-minified build that does not include the sax-js dependency.
-* `imsc.min.js`: Minified build that does not include the sax-js dependency.
+* `imsc.debug.js`: Non-minified UMD build.
+* `imsc.min.js`: Minified UMD build.
+* `main/`: ES modules and TypeScript type declarations, used when the library is imported as an NPM package.
 
-The `build/public_html/libs/imsc.js` files is identical to:
+The `build/public_html/libs/imsc.js` file is identical to:
 * `imsc.debug.js`, if the `build:debug` task is executed.
 * `imsc.min.js`, if the `build:release` task is executed.