JavaScript 获取对象属性数量的实现方法

function objectSize(the_object) {
 /* function to validate the existence of each key
 in the object to get the number of valid keys. */
 var object_size = 0;
 for (key in the_object){
  if (the_object.hasOwnProperty(key)) {
   object_size++;
  }
 }
 return object_size;
}

// Arbitrary object
var something = {
 dog: "cat",
 cat: "dog"
}
console.log(objectSize(something));
// Logs: 2