clamp.js

/*!
 * Clamp.js 0.7.0
 * Based on: https://github.com/xavi160/Clamp.js/commit/e313818da231b8dd8fd603dd9c9a61a9d725c22f
 * Mixins:
 * - https://github.com/josephschmitt/Clamp.js/pull/50
 * - https://github.com/josephschmitt/Clamp.js/pull/49
 *
 * Copyright 2011-2013, Joseph Schmitt http://joe.sh
 * Released under the WTFPL license
 * http://sam.zoy.org/wtfpl/
 */

(function(root, factory) {
  if (typeof define === 'function' && define.amd) {
    // AMD
    define([], factory);
  } else if (typeof exports === 'object') {
    // Node, CommonJS-like
    module.exports = factory();
  } else {
    // Browser globals
    root.$clamp = factory();
  }
}(this, function() {
  /**
   * Clamps a text node.
   * @param {HTMLElement} element. Element containing the text node to clamp.
   * @param {Object} options. Options to pass to the clamper.
   */
  function clamp(element, options) {
    options = options || {};

    var self = this,
      win = window,
      opt = {
        clamp: options.clamp || 2,
        useNativeClamp: typeof(options.useNativeClamp) != 'undefined' ? options.useNativeClamp : true,
        splitOnChars: options.splitOnChars || ['.', '-', '–', '—', ' '], //Split on sentences (periods), hypens, en-dashes, em-dashes, and words (spaces).
        animate: options.animate || false,
        truncationChar: options.truncationChar || '…',
        truncationHTML: options.truncationHTML
      },

      sty = element.style,
      originalText = element.innerHTML,

      supportsNativeClamp = typeof(element.style.webkitLineClamp) != 'undefined',
      clampValue = opt.clamp,
      isCSSValue = clampValue.indexOf && (clampValue.indexOf('px') > -1 || clampValue.indexOf('em') > -1),
      truncationHTMLContainer;

    if (opt.truncationHTML) {
      truncationHTMLContainer = document.createElement('span');
      truncationHTMLContainer.innerHTML = opt.truncationHTML;
    }


    // UTILITY FUNCTIONS __________________________________________________________

    /**
     * Return the current style for an element.
     * @param {HTMLElement} elem The element to compute.
     * @param {string} prop The style property.
     * @returns {number}
     */
    function computeStyle(elem, prop) {
      if (!win.getComputedStyle) {
        win.getComputedStyle = function(el, pseudo) {
          this.el = el;
          this.getPropertyValue = function(prop) {
            var re = /(\-([a-z]){1})/g;
            if (prop == 'float') prop = 'styleFloat';
            if (re.test(prop)) {
              prop = prop.replace(re, function() {
                return arguments[2].toUpperCase();
              });
            }
            return el.currentStyle && el.currentStyle[prop] ? el.currentStyle[prop] : null;
          };
          return this;
        };
      }

      return win.getComputedStyle(elem, null).getPropertyValue(prop);
    }

    /**
     * Returns the maximum number of lines of text that should be rendered based
     * on the current height of the element and the line-height of the text.
     */
    function getMaxLines(height) {
      var availHeight = height || element.clientHeight,
        lineHeight = getLineHeight(element);

      return Math.max(Math.floor(availHeight / lineHeight), 0);
    }

    /**
     * Returns the maximum height a given element should have based on the line-
     * height of the text and the given clamp value.
     */
    function getMaxHeight(clmp) {
      var lineHeight = getLineHeight(element);
      return lineHeight * clmp;
    }

    /**
     * Returns the line-height of an element as an integer.
     */
    function getLineHeight(elem) {
      var lh = computeStyle(elem, 'line-height');
      if (lh == 'normal') {
        // Normal line heights vary from browser to browser. The spec recommends
        // a value between 1.0 and 1.2 of the font size. Using 1.1 to split the diff.
        lh = parseInt(computeStyle(elem, 'font-size')) * 1.2;
      }
      return parseInt(lh);
    }


    // MEAT AND POTATOES (MMMM, POTATOES...) ______________________________________
    var splitOnChars = opt.splitOnChars.slice(0),
      splitChar = splitOnChars[0],
      chunks,
      lastChunk;

    /**
     * Gets an element's last child. That may be another node or a node's contents.
     */
    function getLastChild(elem) {
      if (!elem.lastChild) {
        return;
      }
      //Current element has children, need to go deeper and get last child as a text node
      if (elem.lastChild.children && elem.lastChild.children.length > 0) {
        return getLastChild(Array.prototype.slice.call(elem.children).pop());
      }
      //Handle scenario where the last child is white-space node
      else if (!elem.lastChild || !elem.lastChild.nodeValue || elem.lastChild.nodeValue === '' || elem.lastChild.nodeValue == opt.truncationChar) {
        var sibling = elem.lastChild;
        do {
          if (!sibling) {
            return;
          }
          //TEXT_NODE
          if (sibling.nodeType === 3 && ['', opt.truncationChar].indexOf(sibling.nodeValue) === -1) {
            return sibling;
          }
          if (sibling.lastChild) {
            var lastChild = getLastChild(sibling);
            if (lastChild) {
              return lastChild;
            }
          }
          //Current sibling is pretty useless
          sibling.parentNode.removeChild(sibling);
        } while (sibling = sibling.previousSibling);
      }
      //This is the last child we want, return it
      else {
        return elem.lastChild;
      }
    }

    /**
     * Removes one character at a time from the text until its width or
     * height is beneath the passed-in max param.
     */
    function truncate(target, maxHeight) {
      if (!target || !maxHeight) {
        return;
      }

      /**
       * Resets global variables.
       */
      function reset() {
        splitOnChars = opt.splitOnChars.slice(0);
        splitChar = splitOnChars[0];
        chunks = null;
        lastChunk = null;
      }

      var nodeValue = target.nodeValue.replace(opt.truncationChar, '');

      //Grab the next chunks
      if (!chunks) {
        //If there are more characters to try, grab the next one
        if (splitOnChars.length > 0) {
          splitChar = splitOnChars.shift();
        }
        //No characters to chunk by. Go character-by-character
        else {
          splitChar = '';
        }

        chunks = nodeValue.split(splitChar);
      }

      //If there are chunks left to remove, remove the last one and see if
      // the nodeValue fits.
      if (chunks.length > 1) {
        // console.log('chunks', chunks);
        lastChunk = chunks.pop();
        // console.log('lastChunk', lastChunk);
        applyEllipsis(target, chunks.join(splitChar));
      }
      //No more chunks can be removed using this character
      else {
        chunks = null;
      }

      //Insert the custom HTML before the truncation character
      if (truncationHTMLContainer) {
        target.nodeValue = target.nodeValue.replace(opt.truncationChar, '');
        element.innerHTML = target.nodeValue + ' ' + truncationHTMLContainer.innerHTML + opt.truncationChar;
      }

      //Search produced valid chunks
      if (chunks) {
        //It fits
        if (element.clientHeight <= maxHeight) {
          //There's still more characters to try splitting on, not quite done yet
          if (splitOnChars.length >= 0 && splitChar !== '') {
            applyEllipsis(target, chunks.join(splitChar) + splitChar + lastChunk);
            chunks = null;
          }
          //Finished!
          else {
            return element.innerHTML;
          }
        }
      }
      //No valid chunks produced
      else {
        //No valid chunks even when splitting by letter, time to move
        //on to the next node
        if (splitChar === '') {
          applyEllipsis(target, '');
          target = getLastChild(element);

          reset();
        }
      }

      //If you get here it means still too big, let's keep truncating
      if (opt.animate) {
        setTimeout(function() {
          truncate(target, maxHeight);
        }, opt.animate === true ? 10 : opt.animate);
      } else {
        return truncate(target, maxHeight);
      }
    }

    function applyEllipsis(elem, str) {
      elem.nodeValue = str + opt.truncationChar;
    }


    // CONSTRUCTOR ________________________________________________________________

    if (clampValue == 'auto') {
      clampValue = getMaxLines();
    } else if (isCSSValue) {
      clampValue = getMaxLines(parseInt(clampValue));
    }

    var clampedText;
    if (supportsNativeClamp && opt.useNativeClamp) {
      sty.overflow = 'hidden';
      sty.textOverflow = 'ellipsis';
      sty.webkitBoxOrient = 'vertical';
      sty.display = '-webkit-box';
      sty.webkitLineClamp = clampValue;

      if (isCSSValue) {
        sty.height = opt.clamp + 'px';
      }
    } else {
      var height = getMaxHeight(clampValue);
      if (height < element.clientHeight) {
        clampedText = truncate(getLastChild(element), height);
      }
    }

    return {
      'original': originalText,
      'clamped': clampedText
    };
  }

  return clamp;
}));