li/lib/index.js

Parse the Links header format and return a javascript object.

(function (name, definition, context) {

  //try CommonJS, then AMD (require.js), then use global.

  if (typeof module != 'undefined' && module.exports) module.exports = definition();
  else if (typeof context['define'] == 'function' && context['define']['amd']) define(definition);
  else context[name] = definition();

})('li', function () {
  // compile regular expressions ahead of time for efficiency
  var relsRegExp = /^;\s*([^"=]+)=(?:"([^"]+)"|([^";,]+)(?:[;,]|$))/;
  var sourceRegExp = /^<([^>]*)>/;
  var delimiterRegExp = /^\s*,\s*/;

  return {
    parse: function (linksHeader, options) {
      var match;
      var source;
      var rels;
      var extended = options && options.extended || false;
      var links = [];

      while (linksHeader) {
        linksHeader = linksHeader.trim();

        // Parse `<link>`
        source = sourceRegExp.exec(linksHeader);
        if (!source) break;

        var current = {
          link: source[1]
        };

        // Move cursor
        linksHeader = linksHeader.slice(source[0].length);

        // Parse `; attr=relation` and `; attr="relation"`

        var nextDelimiter = linksHeader.match(delimiterRegExp);
        while(linksHeader && (!nextDelimiter || nextDelimiter.index > 0)) {
          match = relsRegExp.exec(linksHeader);
          if (!match) break;

          // Move cursor
          linksHeader = linksHeader.slice(match[0].length);
          nextDelimiter = linksHeader.match(delimiterRegExp);


          if (match[1] === 'rel' || match[1] === 'rev') {
            // Add either quoted rel or unquoted rel
            rels = (match[2] || match[3]).split(/\s+/);
            current[match[1]] = rels;
          } else {
            current[match[1]] = match[2] || match[3];
          }
        }

        links.push(current);
        // Move cursor
        linksHeader = linksHeader.replace(delimiterRegExp, '');
      }

      if (!extended) {
        return links.reduce(function(result, currentLink) {
          if (currentLink.rel) {
            currentLink.rel.forEach(function(rel) {
              result[rel] = currentLink.link;
            });
          }
          return result;
        }, {});
      }

      return links;
    },
    stringify: function (params) {
      var grouped = Object.keys(params).reduce(function(grouped, key) {
        grouped[params[key]] = grouped[params[key]] || [];
        grouped[params[key]].push(key);
        return grouped;
      }, {});

      var entries = Object.keys(grouped).reduce(function(result, link) {
        return result.concat('<' + link + '>; rel="' + grouped[link].join(' ') + '"');
      }, []);

      return entries.join(', ');
    }
  };

}, this);