Huljo / MowItNow

function AnchorJS(options) {

  'use strict';

  this.options = options || {};

  this._applyRemainingDefaultOptions = function(opts) {

    this.options.icon = this.options.hasOwnProperty('icon') ? opts.icon : '\ue9cb'; // Accepts characters (and also URLs?), like  '#', '¶', '❡', or '§'.

    this.options.visible = this.options.hasOwnProperty('visible') ? opts.visible : 'hover'; // Also accepts 'always'

    this.options.placement = this.options.hasOwnProperty('placement') ? opts.placement : 'right'; // Also accepts 'left'

    this.options.class = this.options.hasOwnProperty('class') ? opts.class : ''; // Accepts any class name.

  };

  this._applyRemainingDefaultOptions(options);

  this.add = function(selector) {

    var elements,

        elsWithIds,

        idList,

        elementID,

        i,

        roughText,

        tidyText,

        index,

        count,

        newTidyText,

        readableID,

        anchor;

    this._applyRemainingDefaultOptions(this.options);

    // Provide a sensible default selector, if none is given.

    if (!selector) {

      selector = 'h1, h2, h3, h4, h5, h6';

    } else if (typeof selector !== 'string') {

      throw new Error('The selector provided to AnchorJS was invalid.');

    }

    elements = document.querySelectorAll(selector);

    if (elements.length === 0) {

      return false;

    }

    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 (elements[i].hasAttribute('id')) {

        elementID = elements[i].getAttribute('id');

      } else {

        roughText = elements[i].textContent;

        // Refine it so it makes a good ID. Strip out non-safe characters, replace

        // spaces with hyphens, truncate to 32 characters, and make toLowerCase.

        //

        // Example string:                                // '⚡⚡⚡ Unicode icons are cool--but they definitely don't belong in a URL fragment.'

        tidyText = roughText.replace(/[^\w\s-]/gi, '')    // ' Unicode icons are cool--but they definitely dont belong in a URL fragment'

                                .replace(/\s+/g, '-')     // '-Unicode-icons-are-cool--but-they-definitely-dont-belong-in-a-URL-fragment'

                                .replace(/-{2,}/g, '-')   // '-Unicode-icons-are-cool-but-they-definitely-dont-belong-in-a-URL-fragment'

                                .substring(0, 64)         // '-Unicode-icons-are-cool-but-they-definitely-dont-belong-in-a-URL'

                                .replace(/^-+|-+$/gm, '') // 'Unicode-icons-are-cool-but-they-definitely-dont-belong-in-a-URL'

                                .toLowerCase();           // 'unicode-icons-are-cool-but-they-definitely-dont-belong-in-a-url'

        // 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;

          }

          // .indexOf is supported in IE9+.

          index = idList.indexOf(newTidyText);

          count += 1;

        } while (index !== -1);

        index = undefined;

        idList.push(newTidyText);

        // Assign it to our element.

        // Currently the setAttribute element is only supported in IE9 and above.

        elements[i].setAttribute('id', newTidyText);

        elementID = newTidyText;

      }

      readableID = elementID.replace(/-/g, ' ');

      // The following code builds the following DOM structure in a more effiecient (albeit opaque) way.

      // '<a class="anchorjs-link ' + this.options.class + '" href="#' + elementID + '" aria-label="Anchor link for: ' + readableID + '" data-anchorjs-icon="' + this.options.icon + '"></a>';

      anchor = document.createElement('a');

      anchor.className = 'anchorjs-link ' + this.options.class;

      anchor.href = '#' + elementID;

      anchor.setAttribute('aria-label', 'Anchor link for: ' + readableID);

      anchor.setAttribute('data-anchorjs-icon', this.options.icon);

      if (this.options.visible === 'always') {

        anchor.style.opacity = '1';

      }

      if (this.options.icon === '\ue9cb') {

        anchor.style.fontFamily = 'anchorjs-icons';

        anchor.style.fontStyle = 'normal';

        anchor.style.fontVariant = 'normal';

        anchor.style.fontWeight = 'normal';

        anchor.style.lineHeight = 1;

      }

      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);

      }

    }

    return this;

  };

  this.remove = function(selector) {

    var domAnchor,

        elements = document.querySelectorAll(selector);

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

      domAnchor = elements[i].querySelector('.anchorjs-link');

      if (domAnchor) {

        elements[i].removeChild(domAnchor);

      }

    }

    return this;

  };

  this._addBaselineStyles = function() {

    // 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";'       +

        '   font-style: normal;'                  +

        '   font-weight: normal;'                 + // Icon from icomoon; 10px wide & 10px tall; 2 empty below & 4 above

        '   src: url(data:application/x-font-ttf;charset=utf-8;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);

  };

}