talisman/keyers/html-text.js

Straightforward fuzzy matching, information retrieval and NLP building blocks for JavaScript.

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: false
});
exports.createKeyer = createKeyer;

var _htmlEntities = require('html-entities');

var ENTITIES = new _htmlEntities.AllHtmlEntities();

/**
 * State constants.
 */
/**
 * Talisman keyers/html-text
 * ==========================
 *
 * Function extracting raw text from HTML representation.
 */
var STATE_TEXT = 0,
    STATE_HTML = 1,
    STATE_TAG_NAME = 2,
    STATE_COMMENT = 3,
    STATE_SKIP = 4;

/**
 * Regexes.
 */
var TAG_START = /[A-Za-z_]/,
    TAG_SPACE = /[\s>]/;

/**
 * Function creating a html to text keyer.
 *
 * @return {function}
 */
function createKeyer() {

  /**
   * Function taking a HTML string and returning raw text.
   *
   * @param  {string} html - Input HTML string.
   * @return {string}
   */
  return function htmlText(html) {
    var state = STATE_TEXT,
        tagName = '',
        buffer = '',
        output = '';

    var quotes = '',
        char = void 0,
        i = void 0,
        l = void 0;

    for (i = 0, l = html.length; i < l; i++) {
      char = html[i];

      // In raw text
      if (state === STATE_TEXT) {
        if (char === '<') {
          state = STATE_TAG_NAME;
          buffer = char;
        } else {
          output += char;
        }
      }

      // Building tag name
      else if (state === STATE_TAG_NAME) {

          // Closing tag
          if (char === '/') {
            state = STATE_HTML;
          }

          // Comments
          else if (char === '!' && html[i + 1] === '-' && html[i + 2] === '-') {
              state = STATE_COMMENT;
              i += 2;
              buffer = '';
            } else if (!tagName) {
              if (!TAG_START.test(char)) {
                state = STATE_TEXT;
                output += buffer + char;
                buffer = '';
              } else {
                tagName = char.toLowerCase();
              }
            } else {
              if (!TAG_SPACE.test(char)) {
                tagName += char.toLowerCase();
              } else {

                if (tagName === 'script' || tagName === 'style') {
                  state = STATE_SKIP;
                } else {
                  state = char === '>' ? STATE_TEXT : STATE_HTML;
                }
              }
            }
        }

        // In HTML
        else if (state === STATE_HTML) {

            // Entering quotes
            if (char === '"' || char === '\'') {
              if (!quotes) quotes = quotes || char;else quotes = '';
            }

            // Closing tag
            else if (!quotes && char === '>') {
                state = STATE_TEXT;
                tagName = '';
              }
          }

          // In comments
          else if (state === STATE_COMMENT) {
              if (buffer === '--' && char === '>') {
                state = STATE_TEXT;
              } else {
                if (buffer.length === 2) buffer = buffer[1];
                buffer += char;
              }
            }
    }

    return ENTITIES.decode(output);
  };
}

exports.default = createKeyer();

// TODO: clean JS
// TODO: clean style
// TODO: CDATA
// TODO: handle <br>, <hr> etc.
// TODO: handle doctype & DTD declaration
// TODO: handle xml declaration
// TODO: innerText && textContent

module.exports = exports['default'];
exports['default'].createKeyer = exports.createKeyer;