code: function(str) {
                  str = blake32(str);
                  var hash = 1315423911, i, ch;
                  for (i = str.length - 1; i >= 0; i--) {
                      ch = str.charCodeAt(i);
                      hash ^= ((hash << 5) + ch + (hash >> 2));
                  }
                  return  (hash & 0x7FFFFFFF);
              }
docs: 获取字符串的哈希值
  
  @param {String} str
  @return {Number} hashCode