code: function (key, val) {
      if ( key.indexOf( '[]' ) !== -1 ) {
        key = key.replace( '[]', '' );
  
        if (isArray(this.queryParams[key])) {
          this.queryParams[key].push(val);
        }
        else {
          this.queryParams[key] = [val];
        }
      }
      else {
        this.queryParams[key] = val;
      }
    }
docs: Update the queryParams property with a new key and value.
  Values for keys with the [] notation are put into arrays
  or pushed into an existing array for that key.
  
  @method _applyQueryParam
  @param {String} key
  @param {String} val