如何计算JavaScript数组对象？ [英] How to count JavaScript array objects?

问题描述

当我有这样的JavaScript数组时：

When I have a JavaScript array like this:

var member = {
    "mother": {
        "name" : "Mary",
        "age" : "48"
    },
    "father": {
        "name" : "Bill",
        "age" : "50"
    },
    "brother": {
        "name" : "Alex",
        "age" : "28"
    }
}

如何计算此数组中的对象？！
我的意思是如何得到一个计数结果3，因为里面只有3个物体：母亲，父亲，兄弟？！

How to count objects in this array?!
I mean how to get a counting result 3, because there're only 3 objects inside: mother, father, brother?!

如果它不是数组，那么如何将其转换为JSON数组？

推荐答案

这不是数组，是一个对象文字，你应该迭代对象的自己的属性并计算它们，例如：

That's not an array, is an object literal, you should iterate over the own properties of the object and count them, e.g.:

function objectLength(obj) {
  var result = 0;
  for(var prop in obj) {
    if (obj.hasOwnProperty(prop)) {
    // or Object.prototype.hasOwnProperty.call(obj, prop)
      result++;
    }
  }
  return result;
}

objectLength(member); // for your example, 3

hasOwnProperty 方法应该用于避免迭代继承的属性，例如

The hasOwnProperty method should be used to avoid iterating over inherited properties, e.g.

var obj = {};
typeof obj.toString; // "function"
obj.hasOwnProperty('toString'); // false, since it's inherited

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