# sax js
  
  A sax-style parser for XML and HTML.
  
  Designed with [node](http://nodejs.org/) in mind, but should work fine in
  the browser or other CommonJS implementations.
  
  ## What This Is
  
  * A very simple tool to parse through an XML string.
  * A stepping stone to a streaming HTML parser.
  * A handy way to deal with RSS and other mostly-ok-but-kinda-broken XML
    docs.
  
  ## What This Is (probably) Not
  
  * An HTML Parser - That's a fine goal, but this isn't it.  It's just
    XML.
  * A DOM Builder - You can use it to build an object model out of XML,
    but it doesn't do that out of the box.
  * XSLT - No DOM = no querying.
  * 100% Compliant with (some other SAX implementation) - Most SAX
    implementations are in Java and do a lot more than this does.
  * An XML Validator - It does a little validation when in strict mode, but
    not much.
  * A Schema-Aware XSD Thing - Schemas are an exercise in fetishistic
    masochism.
  * A DTD-aware Thing - Fetching DTDs is a much bigger job.
  
  ## Regarding `<!DOCTYPE`s and `<!ENTITY`s
  
  The parser will handle the basic XML entities in text nodes and attribute
  values: `&amp; &lt; &gt; &apos; &quot;`. It's possible to define additional
  entities in XML by putting them in the DTD. This parser doesn't do anything
  with that. If you want to listen to the `ondoctype` event, and then fetch
  the doctypes, and read the entities and add them to `parser.ENTITIES`, then
  be my guest.
  
  Unknown entities will fail in strict mode, and in loose mode, will pass
  through unmolested.
  
  ## Usage
  
  ```javascript
  var sax = require("./lib/sax"),
    strict = true, // set to false for html-mode
    parser = sax.parser(strict);
  
  parser.onerror = function (e) {
    // an error happened.
  };
  parser.ontext = function (t) {
    // got some text.  t is the string of text.
  };
  parser.onopentag = function (node) {
    // opened a tag.  node has "name" and "attributes"
  };
  parser.onattribute = function (attr) {
    // an attribute.  attr has "name" and "value"
  };
  parser.onend = function () {
    // parser stream is done, and ready to have more stuff written to it.
  };
  
  parser.write('<xml>Hello, <who name="world">world</who>!</xml>').close();
  
  // stream usage
  // takes the same options as the parser
  var saxStream = require("sax").createStream(strict, options)
  saxStream.on("error", function (e) {
    // unhandled errors will throw, since this is a proper node
    // event emitter.
    console.error("error!", e)
    // clear the error
    this._parser.error = null
    this._parser.resume()
  })
  saxStream.on("opentag", function (node) {
    // same object as above
  })
  // pipe is supported, and it's readable/writable
  // same chunks coming in also go out.
  fs.createReadStream("file.xml")
    .pipe(saxStream)
    .pipe(fs.createWriteStream("file-copy.xml"))
  ```
  
  
  ## Arguments
  
  Pass the following arguments to the parser function.  All are optional.
  
  `strict` - Boolean. Whether or not to be a jerk. Default: `false`.
  
  `opt` - Object bag of settings regarding string formatting.  All default to `false`.
  
  Settings supported:
  
  * `trim` - Boolean. Whether or not to trim text and comment nodes.
  * `normalize` - Boolean. If true, then turn any whitespace into a single
    space.
  * `lowercase` - Boolean. If true, then lowercase tag names and attribute names
    in loose mode, rather than uppercasing them.
  * `xmlns` - Boolean. If true, then namespaces are supported.
  * `position` - Boolean. If false, then don't track line/col/position.
  * `strictEntities` - Boolean. If true, only parse [predefined XML
    entities](http://www.w3.org/TR/REC-xml/#sec-predefined-ent)
    (`&amp;`, `&apos;`, `&gt;`, `&lt;`, and `&quot;`)
  
  ## Methods
  
  `write` - Write bytes onto the stream. You don't have to do this all at
  once. You can keep writing as much as you want.
  
  `close` - Close the stream. Once closed, no more data may be written until
  it is done processing the buffer, which is signaled by the `end` event.
  
  `resume` - To gracefully handle errors, assign a listener to the `error`
  event. Then, when the error is taken care of, you can call `resume` to
  continue parsing. Otherwise, the parser will not continue while in an error
  state.
  
  ## Members
  
  At all times, the parser object will have the following members:
  
  `line`, `column`, `position` - Indications of the position in the XML
  document where the parser currently is looking.
  
  `startTagPosition` - Indicates the position where the current tag starts.
  
  `closed` - Boolean indicating whether or not the parser can be written to.
  If it's `true`, then wait for the `ready` event to write again.
  
  `strict` - Boolean indicating whether or not the parser is a jerk.
  
  `opt` - Any options passed into the constructor.
  
  `tag` - The current tag being dealt with.
  
  And a bunch of other stuff that you probably shouldn't touch.
  
  ## Events
  
  All events emit with a single argument. To listen to an event, assign a
  function to `on<eventname>`. Functions get executed in the this-context of
  the parser object. The list of supported events are also in the exported
  `EVENTS` array.
  
  When using the stream interface, assign handlers using the EventEmitter
  `on` function in the normal fashion.
  
  `error` - Indication that something bad happened. The error will be hanging
  out on `parser.error`, and must be deleted before parsing can continue. By
  listening to this event, you can keep an eye on that kind of stuff. Note:
  this happens *much* more in strict mode. Argument: instance of `Error`.
  
  `text` - Text node. Argument: string of text.
  
  `doctype` - The `<!DOCTYPE` declaration. Argument: doctype string.
  
  `processinginstruction` - Stuff like `<?xml foo="blerg" ?>`. Argument:
  object with `name` and `body` members. Attributes are not parsed, as
  processing instructions have implementation dependent semantics.
  
  `sgmldeclaration` - Random SGML declarations. Stuff like `<!ENTITY p>`
  would trigger this kind of event. This is a weird thing to support, so it
  might go away at some point. SAX isn't intended to be used to parse SGML,
  after all.
  
  `opentagstart` - Emitted immediately when the tag name is available,
  but before any attributes are encountered.  Argument: object with a
  `name` field and an empty `attributes` set.  Note that this is the
  same object that will later be emitted in the `opentag` event.
  
  `opentag` - An opening tag. Argument: object with `name` and `attributes`.
  In non-strict mode, tag names are uppercased, unless the `lowercase`
  option is set.  If the `xmlns` option is set, then it will contain
  namespace binding information on the `ns` member, and will have a
  `local`, `prefix`, and `uri` member.
  
  `closetag` - A closing tag. In loose mode, tags are auto-closed if their
  parent closes. In strict mode, well-formedness is enforced. Note that
  self-closing tags will have `closeTag` emitted immediately after `openTag`.
  Argument: tag name.
  
  `attribute` - An attribute node.  Argument: object with `name` and `value`.
  In non-strict mode, attribute names are uppercased, unless the `lowercase`
  option is set.  If the `xmlns` option is set, it will also contains namespace
  information.
  
  `comment` - A comment node.  Argument: the string of the comment.
  
  `opencdata` - The opening tag of a `<![CDATA[` block.
  
  `cdata` - The text of a `<![CDATA[` block. Since `<![CDATA[` blocks can get
  quite large, this event may fire multiple times for a single block, if it
  is broken up into multiple `write()`s. Argument: the string of random
  character data.
  
  `closecdata` - The closing tag (`]]>`) of a `<![CDATA[` block.
  
  `opennamespace` - If the `xmlns` option is set, then this event will
  signal the start of a new namespace binding.
  
  `closenamespace` - If the `xmlns` option is set, then this event will
  signal the end of a namespace binding.
  
  `end` - Indication that the closed stream has ended.
  
  `ready` - Indication that the stream has reset, and is ready to be written
  to.
  
  `noscript` - In non-strict mode, `<script>` tags trigger a `"script"`
  event, and their contents are not checked for special xml characters.
  If you pass `noscript: true`, then this behavior is suppressed.
  
  ## Reporting Problems
  
  It's best to write a failing test if you find an issue.  I will always
  accept pull requests with failing tests if they demonstrate intended
  behavior, but it is very hard to figure out what issue you're describing
  without a test.  Writing a test is also the best way for you yourself
  to figure out if you really understand the issue you think you have with
  sax-js.