如何访问 JSON 对象数组的第一个元素？

Question

I exptect that mandrill_events only contains one object. How do I access its event-property ?

var req = { mandrill_events: '[{"event":"inbound","ts":1426249238}]' }

Answer 1

var req = { mandrill_events: '[{"event":"inbound","ts":1426249238}]' }

console.log(Object.keys(req)[0]);

Make any Object array ( req ), then simply do Object.keys(req)[0] to pick the first key in the Object array.

Answer 2

To answer your titular question, you use [0] to access the first element, but as it stands mandrill_events contains a string not an array, so mandrill_events[0] will just get you the first character, '['.

So either correct your source to:

var req = { mandrill_events: [{"event":"inbound","ts":1426249238}] };

and then req.mandrill_events[0] , or if you're stuck with it being a string, parse the JSON the string contains:

var req = { mandrill_events: '[{"event":"inbound","ts":1426249238}]' };
var mandrill_events = JSON.parse(req.mandrill_events);
var result = mandrill_events[0];

Answer 3

the event property seems to be string first you have to parse it to json :

 var req = { mandrill_events: '[{"event":"inbound","ts":1426249238}]' };
 var event = JSON.parse(req.mandrill_events);
 var ts =  event[0].ts

Answer 4

'[{"event":"inbound","ts":1426249238}]' is a string, you cannot access any properties there. You will have to parse it to an object, with JSON.parse() and then handle it like a normal object

Answer 5

I'll explain this with a general example:

var obj = { name: "John", age: 30, city: "New York" };
var result = obj[Object.keys(obj)[0]];

The result variable will have the value "John"

Answer 6

用 Javascript 解析后，试试这个：

mandrill_events[0].event

Answer 7

Assuming thant the content of mandrill_events is an object (not a string), you can also use shift() function:

var req = { mandrill_events: [{"event":"inbound","ts":1426249238}] };
var event-property = req.mandrill_events.shift().event;