URL Parameters as an object

params.js

// Could be any query string
var parameters = document.location.search;

var parametersObject = parameters
  // Skip the "?" at the beginning of the string
  .substr(1)
  // Split into an array of individual parameters
  .split("&")
  // Split each parameter into an array of its key and value
  .map(function(a){
    return a.split("=");
  })
  // Build a single depth object out of each key/value pair
  .reduce(function(m,i){
    // If this key already exists, its an array, so append to it instead of defining it
    if(m[i[0]]) {
      // Make this into an Array if it isn't one already
      if(m[i[0]] && m[i[0]].constructor !== Array) {
        m[i[0]] = [m[i[0]]];
      }
      m[i[0]].push(decodeURIComponent(i[1]));
    } else {
      m[i[0]] = decodeURIComponent(i[1]);
    }
    return m;
  }, {});

params.min.js

document.location.search.substr(1).split("&").map((a) => a.split("=")).reduce((m,i) => { if(m[i[0]]) { if(m[i[0]] && m[i[0]].constructor !== Array) { m[i[0]] = [m[i[0]]] } m[i[0]].push(decodeURIComponent(i[1])) } else { m[i[0]] = decodeURIComponent(i[1]) } return m }, {})