Append query to anchor

forward-query-strings.js

/**
 * forward-query-strings.js
 *
 * Harrison DeStefano
 * A utility to append query strings to a href value.
 * December 05, 2016
 */

'use strict'

var FowardQueryStrings = function(options) {
  this.defaults = {
    matchHref: options.matchHref || false,
    hrefValue: options.hrefValue || null
  },
    this.store = {
      querystring: null
    }
};

/*
 * Validate URI for query and add value to FQS store.
 */
FowardQueryStrings.prototype.retrieve = function(){
  var query = window.location.href.indexOf('?');
  if(query >= 0){
    this.store.querystring = window.location.href.substring(query);
  }
};

/*
 * Inject the query string into href values as defined.
 */
FowardQueryStrings.prototype.inject = function(){
  if(!this.store.querystring){
    return;
  }
  var anchors = document.querySelectorAll('a');
  for(var a in anchors){
    if(anchors[a].href){
      var anchorURI = getBaseURI(anchors[a].href);
      var defaultURI = getBaseURI(this.defaults.hrefValue);
      if(this.defaults.matchHref && defaultURI === anchorURI || this.defaults.matchHref === false){
        anchors[a].href = anchors[a].href + this.store.querystring;
      }
    }
  }
  
  /*
   * Find the base URI
   * @param uri (string) The URI to strip to base
   * @return uri (string) The base URI or a null reference
   */
  function getBaseURI(uri){
    var regex = new RegExp('^.+?[^\/:](?=[?\/]|$)');
    var base = regex.exec(uri);
    return base ? base[0] : null;
  }
};

window.addEventListener('load', function(){
  var options = { matchHref: true, hrefValue: 'https://donate.weizmann-usa.org' };
  var fqs = new FowardQueryStrings(options);
  fqs.retrieve();
  fqs.inject();
});