text: /* eslint-env amd */
  /* globals module:false */
  
  // https://github.com/umdjs/umd/blob/master/templates/returnExports.js
  (function (root, factory) {
    'use strict';
  
    if (typeof define === 'function' && define.amd) {
      // AMD. Register as an anonymous module.
      define([], factory);
    } else if (typeof module === 'object' && module.exports) {
      // Node. Does not work with strict CommonJS, but
      // only CommonJS-like environments that support module.exports,
      // like Node.
      module.exports = factory();
    } else {
      // Browser globals (root is window)
      root.AnchorJS = factory();
      root.anchors = new root.AnchorJS();
    }
  }(this, function () {
    'use strict';
  
    function AnchorJS(options) {
      this.options = options || {};
      this.elements = [];
  
      /**
       * Assigns options to the internal options object, and provides defaults.
       * @param {Object} opts - Options object
       */
      function _applyRemainingDefaultOptions(opts) {
        opts.icon = opts.hasOwnProperty('icon') ? opts.icon : '\ue9cb'; // Accepts characters (and also URLs?), like  '#', '¶', '❡', or '§'.
        opts.visible = opts.hasOwnProperty('visible') ? opts.visible : 'hover'; // Also accepts 'always' & 'touch'
        opts.placement = opts.hasOwnProperty('placement') ? opts.placement : 'right'; // Also accepts 'left'
        opts.ariaLabel = opts.hasOwnProperty('ariaLabel') ? opts.ariaLabel : 'Anchor'; // Accepts any text.
        opts.class = opts.hasOwnProperty('class') ? opts.class : ''; // Accepts any class name.
        opts.base = opts.hasOwnProperty('base') ? opts.base : ''; // Accepts any base URI.
        // Using Math.floor here will ensure the value is Number-cast and an integer.
        opts.truncate = opts.hasOwnProperty('truncate') ? Math.floor(opts.truncate) : 64; // Accepts any value that can be typecast to a number.
        opts.titleText = opts.hasOwnProperty('titleText') ? opts.titleText : ''; // Accepts any text.
      }
  
      _applyRemainingDefaultOptions(this.options);
  
      /**
       * Checks to see if this device supports touch. Uses criteria pulled from Modernizr:
       * https://github.com/Modernizr/Modernizr/blob/da22eb27631fc4957f67607fe6042e85c0a84656/feature-detects/touchevents.js#L40
       * @return {Boolean} - true if the current device supports touch.
       */
      this.isTouchDevice = function() {
        return !!(('ontouchstart' in window) || window.DocumentTouch && document instanceof DocumentTouch);
      };
  
      /**
       * Add anchor links to page elements.
       * @param  {String|Array|Nodelist} selector - A CSS selector for targeting the elements you wish to add anchor links
       *                                            to. Also accepts an array or nodeList containing the relavant elements.
       * @return {this}                           - The AnchorJS object
       */
      this.add = function(selector) {
        var elements,
            elsWithIds,
            idList,
            elementID,
            i,
            index,
            count,
            tidyText,
            newTidyText,
            anchor,
            visibleOptionToUse,
            hrefBase,
            indexesToDrop = [];
  
        // We reapply options here because somebody may have overwritten the default options object when setting options.
        // For example, this overwrites all options but visible:
        //
        // anchors.options = { visible: 'always'; }
        _applyRemainingDefaultOptions(this.options);
  
        visibleOptionToUse = this.options.visible;
        if (visibleOptionToUse === 'touch') {
          visibleOptionToUse = this.isTouchDevice() ? 'always' : 'hover';
        }
  
        // Provide a sensible default selector, if none is given.
        if (!selector) {
          selector = 'h2, h3, h4, h5, h6';
        }
  
        elements = _getElements(selector);
  
        if (elements.length === 0) {
          return this;
        }
  
        _addBaselineStyles();
  
        // We produce a list of existing IDs so we don't generate a duplicate.
        elsWithIds = document.querySelectorAll('[id]');
        idList = [].map.call(elsWithIds, function assign(el) {
          return el.id;
        });
  
        for (i = 0; i < elements.length; i++) {
          if (this.hasAnchorJSLink(elements[i])) {
            indexesToDrop.push(i);
            continue;
          }
  
          if (elements[i].hasAttribute('id')) {
            elementID = elements[i].getAttribute('id');
          } else if (elements[i].hasAttribute('data-anchor-id')) {
            elementID = elements[i].getAttribute('data-anchor-id');
          } else {
            tidyText = this.urlify(elements[i].textContent);
  
            // Compare our generated ID to existing IDs (and increment it if needed)
            // before we add it to the page.
            newTidyText = tidyText;
            count = 0;
            do {
              if (index !== undefined) {
                newTidyText = tidyText + '-' + count;
              }
  
              index = idList.indexOf(newTidyText);
              count += 1;
            } while (index !== -1);
            index = undefined;
            idList.push(newTidyText);
  
            elements[i].setAttribute('id', newTidyText);
            elementID = newTidyText;
          }
  
          // The following code efficiently builds this DOM structure:
          // `<a class="anchorjs-link ${this.options.class}"
          //     aria-label="${this.options.ariaLabel}"
          //     data-anchorjs-icon="${this.options.icon}"
          //     title="${this.options.titleText}"
          //     href="this.options.base#${elementID}">
          // </a>;`
          anchor = document.createElement('a');
          anchor.className = 'anchorjs-link ' + this.options.class;
          anchor.setAttribute('aria-label', this.options.ariaLabel);
          anchor.setAttribute('data-anchorjs-icon', this.options.icon);
          if (this.options.titleText) {
            anchor.title = this.options.titleText;
          }
          // Adjust the href if there's a <base> tag. See https://github.com/bryanbraun/anchorjs/issues/98
          hrefBase = document.querySelector('base') ? window.location.pathname + window.location.search : '';
          hrefBase = this.options.base || hrefBase;
          anchor.href = hrefBase + '#' + elementID;
  
          if (visibleOptionToUse === 'always') {
            anchor.style.opacity = '1';
          }
  
          if (this.options.icon === '\ue9cb') {
            anchor.style.font = '1em/1 anchorjs-icons';
  
            // We set lineHeight = 1 here because the `anchorjs-icons` font family could otherwise affect the
            // height of the heading. This isn't the case for icons with `placement: left`, so we restore
            // line-height: inherit in that case, ensuring they remain positioned correctly. For more info,
            // see https://github.com/bryanbraun/anchorjs/issues/39.
            if (this.options.placement === 'left') {
              anchor.style.lineHeight = 'inherit';
            }
          }
  
          if (this.options.placement === 'left') {
            anchor.style.position = 'absolute';
            anchor.style.marginLeft = '-1em';
            anchor.style.paddingRight = '0.5em';
            elements[i].insertBefore(anchor, elements[i].firstChild);
          } else { // if the option provided is `right` (or anything else).
            anchor.style.paddingLeft = '0.375em';
            elements[i].appendChild(anchor);
          }
        }
  
        for (i = 0; i < indexesToDrop.length; i++) {
          elements.splice(indexesToDrop[i] - i, 1);
        }
        this.elements = this.elements.concat(elements);
  
        return this;
      };
  
      /**
       * Removes all anchorjs-links from elements targeted by the selector.
       * @param  {String|Array|Nodelist} selector - A CSS selector string targeting elements with anchor links,
       *                                            OR a nodeList / array containing the DOM elements.
       * @return {this}                           - The AnchorJS object
       */
      this.remove = function(selector) {
        var index,
            domAnchor,
            elements = _getElements(selector);
  
        for (var i = 0; i < elements.length; i++) {
          domAnchor = elements[i].querySelector('.anchorjs-link');
          if (domAnchor) {
            // Drop the element from our main list, if it's in there.
            index = this.elements.indexOf(elements[i]);
            if (index !== -1) {
              this.elements.splice(index, 1);
            }
            // Remove the anchor from the DOM.
            elements[i].removeChild(domAnchor);
          }
        }
        return this;
      };
  
      /**
       * Removes all anchorjs links. Mostly used for tests.
       */
      this.removeAll = function() {
        this.remove(this.elements);
      };
  
      /**
       * Urlify - Refine text so it makes a good ID.
       *
       * To do this, we remove apostrophes, replace non-safe characters with hyphens,
       * remove extra hyphens, truncate, trim hyphens, and make lowercase.
       *
       * @param  {String} text - Any text. Usually pulled from the webpage element we are linking to.
       * @return {String}      - hyphen-delimited text for use in IDs and URLs.
       */
      this.urlify = function(text) {
        // Regex for finding the non-safe URL characters (many need escaping): & +$,:;=?@"#{}|^~[`%!'<>]./()*\ (newlines, tabs, backspace, & vertical tabs)
        var nonsafeChars = /[& +$,:;=?@"#{}|^~[`%!'<>\]\.\/\(\)\*\\\n\t\b\v]/g,
            urlText;
  
        // The reason we include this _applyRemainingDefaultOptions is so urlify can be called independently,
        // even after setting options. This can be useful for tests or other applications.
        if (!this.options.truncate) {
          _applyRemainingDefaultOptions(this.options);
        }
  
        // Note: we trim hyphens after truncating because truncating can cause dangling hyphens.
        // Example string:                      // " ⚡⚡ Don't forget: URL fragments should be i18n-friendly, hyphenated, short, and clean."
        urlText = text.trim()                   // "⚡⚡ Don't forget: URL fragments should be i18n-friendly, hyphenated, short, and clean."
          .replace(/\'/gi, '')                  // "⚡⚡ Dont forget: URL fragments should be i18n-friendly, hyphenated, short, and clean."
          .replace(nonsafeChars, '-')           // "⚡⚡-Dont-forget--URL-fragments-should-be-i18n-friendly--hyphenated--short--and-clean-"
          .replace(/-{2,}/g, '-')               // "⚡⚡-Dont-forget-URL-fragments-should-be-i18n-friendly-hyphenated-short-and-clean-"
          .substring(0, this.options.truncate)  // "⚡⚡-Dont-forget-URL-fragments-should-be-i18n-friendly-hyphenated-"
          .replace(/^-+|-+$/gm, '')             // "⚡⚡-Dont-forget-URL-fragments-should-be-i18n-friendly-hyphenated"
          .toLowerCase();                       // "⚡⚡-dont-forget-url-fragments-should-be-i18n-friendly-hyphenated"
  
        return urlText;
      };
  
      /**
       * Determines if this element already has an AnchorJS link on it.
       * Uses this technique: http://stackoverflow.com/a/5898748/1154642
       * @param    {HTMLElement}  el - a DOM node
       * @return   {Boolean}     true/false
       */
      this.hasAnchorJSLink = function(el) {
        var hasLeftAnchor = el.firstChild && ((' ' + el.firstChild.className + ' ').indexOf(' anchorjs-link ') > -1),
            hasRightAnchor = el.lastChild && ((' ' + el.lastChild.className + ' ').indexOf(' anchorjs-link ') > -1);
  
        return hasLeftAnchor || hasRightAnchor || false;
      };
  
      /**
       * Turns a selector, nodeList, or array of elements into an array of elements (so we can use array methods).
       * It also throws errors on any other inputs. Used to handle inputs to .add and .remove.
       * @param  {String|Array|Nodelist} input - A CSS selector string targeting elements with anchor links,
       *                                         OR a nodeList / array containing the DOM elements.
       * @return {Array} - An array containing the elements we want.
       */
      function _getElements(input) {
        var elements;
        if (typeof input === 'string' || input instanceof String) {
          // See https://davidwalsh.name/nodelist-array for the technique transforming nodeList -> Array.
          elements = [].slice.call(document.querySelectorAll(input));
        // I checked the 'input instanceof NodeList' test in IE9 and modern browsers and it worked for me.
        } else if (Array.isArray(input) || input instanceof NodeList) {
          elements = [].slice.call(input);
        } else {
          throw new Error('The selector provided to AnchorJS was invalid.');
        }
        return elements;
      }
  
      /**
       * _addBaselineStyles
       * Adds baseline styles to the page, used by all AnchorJS links irregardless of configuration.
       */
      function _addBaselineStyles() {
        // We don't want to add global baseline styles if they've been added before.
        if (document.head.querySelector('style.anchorjs') !== null) {
          return;
        }
  
        var style = document.createElement('style'),
            linkRule =
            ' .anchorjs-link {'                       +
            '   opacity: 0;'                          +
            '   text-decoration: none;'               +
            '   -webkit-font-smoothing: antialiased;' +
            '   -moz-osx-font-smoothing: grayscale;'  +
            ' }',
            hoverRule =
            ' *:hover > .anchorjs-link,'              +
            ' .anchorjs-link:focus  {'                +
            '   opacity: 1;'                          +
            ' }',
            anchorjsLinkFontFace =
            ' @font-face {'                           +
            '   font-family: "anchorjs-icons";'       + // Icon from icomoon; 10px wide & 10px tall; 2 empty below & 4 above
            '   src: url(data:n/a;base64,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) format("truetype");' +
            ' }',
            pseudoElContent =
            ' [data-anchorjs-icon]::after {'          +
            '   content: attr(data-anchorjs-icon);'   +
            ' }',
            firstStyleEl;
  
        style.className = 'anchorjs';
        style.appendChild(document.createTextNode('')); // Necessary for Webkit.
  
        // We place it in the head with the other style tags, if possible, so as to
        // not look out of place. We insert before the others so these styles can be
        // overridden if necessary.
        firstStyleEl = document.head.querySelector('[rel="stylesheet"], style');
        if (firstStyleEl === undefined) {
          document.head.appendChild(style);
        } else {
          document.head.insertBefore(style, firstStyleEl);
        }
  
        style.sheet.insertRule(linkRule, style.sheet.cssRules.length);
        style.sheet.insertRule(hoverRule, style.sheet.cssRules.length);
        style.sheet.insertRule(pseudoElContent, style.sheet.cssRules.length);
        style.sheet.insertRule(anchorjsLinkFontFace, style.sheet.cssRules.length);
      }
    }
  
    return AnchorJS;
  }));