问在javascript中解析QueryString

EN

function parseQueryString() {

    // Use location.search to access query string instead
    const qs = window.location.search.replace('?', '');

    const items = qs.split('&');

    // Consider using reduce to create the data mapping
    return items.reduce((data, item) => {

      const [rawKey, rawValue] = item.split('=');
      const key = decodeURIComponent(rawKey);
      const value = decodeURIComponent(rawValue);

      // Sometimes a query string can have multiple values 
      // for the same key, so to factor that case in, you
      // could collect an array of values for the same key
      if(data[key] !== undefined) {
        
        // If the value for this key was not previously an
        // array, update it
        if(!Array.isArray(data[key])) {
          data[key] = [ data[key] ]
        }       
        
        data[key].push(value)
      }
      else {
        
        data[key] = value
      }

      return data

    }, {})
}

var urlParams = new URLSearchParams(window.location.search);
var activeCategory, activeComponent;

  // sets the active navigation if there are query paramenters in the url
  if(urlParams.has('category')) {
    activeCategory = urlParams.get('category');
    activeComponent= urlParams.get('component');
  } else {
    activeCategory = null;
    activeComponent= null;
  }

  //eg: www.myShop.com.au?category=music&component=guitar
  // gives activeCategory="music"  and activeComponent = "guitar"

   //eg: www.myShop.com.au
  // gives activeCategory = null  and activeCcomponent = null

 var qsarr = window.location.href.split('?');
  if(qsarr.length > 1)
  var qs=qsarr[1];