read-excel-file/modules/xlsx/parseSharedStrings.js

Read `.xlsx` files in a web browser or in Node.js

/**
 * Parses `sharedStrings.xml` file.
 * @param {string} content
 * @param {function} parseXml — SAX XML parser.
 * @returns {Promise<string[]>}
 */
export default function parseSharedStrings(content, parseXml) {
  var state = createInitialState();
  return parseXml(content, state, onOpenTag, onCloseTag, onText).then(function () {
    return getResultFromState(state);
  });
  function createInitialState() {
    return {
      si: undefined,
      strings: []
    };
  }
  function getResultFromState(state) {
    return state.strings;
  }

  // In an XLSX `sharedStrings.xml` file, a <si/> (string item) element can have
  // either a single child <t/> element (meaning that "rich formatting" is not used)
  // or multiple child <r/> elements (meaning that "rich formatting" is used).
  function onOpenTag(tagName, attributes, state) {
    if (tagName === 'si') {
      state.si = createInitialStateInSharedString();
    } else if (state.si) {
      onOpenTagInSharedString(tagName, attributes, state.si);
    }
  }
  function onCloseTag(tagName, state) {
    if (tagName === 'si') {
      state.strings.push(state.si.string);
      state.si = undefined;
    } else if (state.si) {
      onCloseTagInSharedString(tagName, state.si);
    }
  }
  function onText(text, state) {
    if (state.si) {
      onTextInSharedString(text, state.si);
    }
  }

  // Shared String

  function createInitialStateInSharedString() {
    return {
      t: false,
      r: false,
      rPh: false,
      string: ''
    };
  }

  // In an XLSX `sharedStrings.xml` file, a <si/> (string item) element can have
  // either a single child <t/> element (meaning that "rich formatting" is not used)
  // or multiple child <r/> elements (meaning that "rich formatting" is used).
  function onOpenTagInSharedString(tagName, attributes, state) {
    // The possible children of <si> are:
    // * <t>: Represents a simple text string. For plain text, this is the only child.
    // * <r>: Represents a rich text run. When a cell contains text where only some words are bolded, colored, or styled differently, multiple <r> elements are used to break the text into formatted segments.
    // * <rPh> (Phonetic Run): Used primarily for East Asian languages to provide phonetic reading/pronunciation data (e.g., furigana in Japanese). It associates a phonetic pronunciation run right alongside the base string text tag <t>.
    // * <phoneticPr>: Defines the phonetic properties used for East Asian languages, specifically mapping how strings should be read for sorting and pronunciation.
    if (tagName === 't') {
      state.t = true;
    } else if (tagName === 'r') {
      // The possible children of <r/> are:
      // * <rPr> (Run Properties): The formatting properties for the text (font, size, color, bold, italic, etc.).
      // * <t> (Text): The actual text payload.
      // * <rPh> (Phonetic Run): Phonetic pronunciation guidance (used for East Asian languages like Japanese). It associates a phonetic pronunciation run right alongside the base string text tag <t>.
      state.r = true;
    } else if (tagName === 'rPh') {
      // The possible children of <rPh/> are:
      // * <t> (Text):  Contains the actual phonetic text or reading (usually in Katakana for Japanese) that corresponds to the associated character string.
      state.rPh = true;
    }
  }
  function onCloseTagInSharedString(tagName, state) {
    if (tagName === 't') {
      state.t = false;
    } else if (tagName === 'r') {
      state.r = false;
    } else if (tagName === 'rPh') {
      state.rPh = false;
    }
  }
  function onTextInSharedString(text, state) {
    if (state.rPh) {
      // Ignore anything inside `<rPh/>` tags
    } else if (state.t) {
      if (state.r) {
        // An `<r/>` element could contain multiple `<t/>` elements,
        // the text content from all of which should be concatenated.
        state.string += text;
      } else {
        state.string = text;
      }
    }
  }
}
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