HTML文本截取库

/**
 * [trimHtml description]
 * HTML文本截取库
 * @param  {String} html
 * @param  {Object} options
 * @return {Object}
 */
export const trimHtml = (html, options) => {

  options = options || {};

  var limit = options.limit || 100,
    preserveTags = (typeof options.preserveTags !== 'undefined') ? options.preserveTags : true,
    wordBreak = (typeof options.wordBreak !== 'undefined') ? options.wordBreak : false,
    suffix = options.suffix || '...',
    moreLink = options.moreLink || '',
    moreText = options.moreText || '»',
    preserveWhiteSpace = options.preserveWhiteSpace || false;


  var arr = html.replace(/</g, "\n<")
    .replace(/>/g, ">\n")
    .replace(/\n\n/g, "\n")
    .replace(/^\n/g, "")
    .replace(/\n$/g, "")
    .split("\n");


  var sum = 0,
    row, cut, add,
    tagMatch,
    tagName,
    tagStack = [],
    more = false;

  for (var i = 0; i < arr.length; i++) {

    row = arr[i];
    let rowCut = "";

    // count multiple spaces as one character
    if (!preserveWhiteSpace) {
      rowCut = row.replace(/[ ]+/g, ' ');
    } else {
      rowCut = row;
    }

    if (!row.length) {
      continue;
    }

    var charArr = getCharArr(rowCut);

    if (row[0] !== "<") {

      if (sum >= limit) {
        row = "";
      } else if ((sum + charArr.length) >= limit) {

        cut = limit - sum;

        if (charArr[cut - 1] === ' ') {
          while (cut) {
            cut -= 1;
            if (charArr[cut - 1] !== ' ') {
              break;
            }
          }
        } else {

          add = charArr.slice(cut).indexOf(' ');

          // break on halh of word
          if (!wordBreak) {
            if (add !== -1) {
              cut += add;
            } else {
              cut = row.length;
            }
          }
        }

        row = charArr.slice(0, cut).join('') + suffix;

        if (moreLink) {
          row += '<a href="' + moreLink + '" style="display:inline">' + moreText + '</a>';
        }

        sum = limit;
        more = true;
      } else {
        sum += charArr.length;
      }
    } else if (!preserveTags) {
      row = '';
    } else if (sum >= limit) {

      tagMatch = row.match(/[a-zA-Z]+/);
      tagName = tagMatch ? tagMatch[0] : '';

      if (tagName) {
        if (row.substring(0, 2) !== '</') {

          tagStack.push(tagName);
          row = '';
        } else {

          while (tagStack[tagStack.length - 1] !== tagName && tagStack.length) {
            tagStack.pop();
          }

          if (tagStack.length) {
            row = '';
          }

          tagStack.pop();
        }
      } else {
        row = '';
      }
    }

    arr[i] = row;
  }

  return {
    html: arr.join("\n").replace(/\n/g, " ").replaceAll("  ", " ").replaceAll("  ", " "),
    more: more
  };
};

// count symbols like one char
function getCharArr(rowCut) {
  var charArr = [],
    subRow,
    match,
    char;

  for (var i = 0; i < rowCut.length; i++) {

    subRow = rowCut.substring(i);
    match = subRow.match(/^&[a-z0-9#]+;/);

    if (match) {
      char = match[0];
      charArr.push(char);
      i += (char.length - 1);
    } else {
      charArr.push(rowCut[i]);
    }
  }

  return charArr;
}