用JSON计算键/值 [英] Count Key/Values in JSON
问题描述
可能重复:
Javascript关联数组的长度
我有一个JSON,看起来像这样:
I have a JSON that looks like this:
Object:
www.website1.com : "dogs"
www.website2.com : "cats"
>__proto__ : Object
当我这样做时打印:
console.log(obj);
我正在尝试获取此JSON中的项目计数,obj.length返回undefined和obj [0] .length返回
I am trying to get the count of the items inside this JSON, obj.length returns "undefined" and obj[0].length returns
未捕获TypeError:无法读取未定义属性'length'
Uncaught TypeError: Cannot read property 'length' of undefined
在这种情况下,我希望长度返回2。我怎样才能找到计数?
I would expect a length to return "2" in this case. How can I find the count?
谢谢!
推荐答案
你必须自己计算:
function count(obj) {
var count=0;
for(var prop in obj) {
if (obj.hasOwnProperty(prop)) {
++count;
}
}
return count;
}
虽然现在我看到了关于这个问题的第一条评论,但是有很多该页面上更好的答案。单行,可能同样快但不快:
Although now that I saw the first comment on the question, there is a much nicer answer on that page. One-liner, probably just as fast if not faster:
function count(obj) { return Object.keys(obj).length; }
请注意,支持 Object.keys()
目前还没有跨浏览器。
Be aware though, support for Object.keys()
doesn't seem cross-browser just yet.
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