javascript计算对象长度的方法

var obj = {"c1":1,"c2":2};
function countProperties(obj){
  for(var property in obj){
    if(Object.prototype.hasOwnProperty.call(obj,property){
      count++;
    })
  }
  return count;
}
var len = obj.length;
console.log(len);//结果为2

var obj = {"c1":1,"c2":2};
var arr = Object.keys(obj);
var len = arr.length;
console.log(len);//结果为2