js Gets the implementation code for the actual length of objects and arrays and the actual number of elements

js Gets the implementation code for the actual length of objects and arrays and the actual number of elements

/* Get object, length of array, number of elements 
   *@param obj  To calculate the length of an element, you can object , array , string
  */
  function count(obj){
    var objType = typeof obj;
    if(objType == "string"){
      return obj.length;
    }else if(objType == "object"){
      var objLen = 0;
      for(var i in obj){
        objLen++;
      }
      return objLen;
    }
    return false;
  }