How do I recognize an empty JSON object in JS returned by my Rails controller?

Question

How do I check for an empty JSON object in Javascript? I thought the key was

var isEmpty = (response || []).length === 0;

but this isn't it. In my JS console, I have tried

jsonresp = {}
{}
jsonresp.length
undefined

What's driving this is I have a Ruby on Rails controller that is returning the following

render json: job_id.eql?(cur_job_id) ? {} : json_obj

In the case where the controller returns the "{}" is where I'm having trouble on the JS side recognizing if it is empty or not.

`if(Object.keys({}).length > 0){console.log("YaY")}` – 7urkm3n Mar 14 '18 at 16:55 — 7urkm3n, Mar 14 '18 at 16:55

score 1 · Answer 1 · answered Mar 14 '18 at 16:32

1

You can also try:

if (typeof jsonresp == 'undefined' || typeof jsonresp == 'null'){

// some logic here

}

answered Mar 14 '18 at 16:32

Sanjay Vig

score 0 · Answer 2 · answered Mar 14 '18 at 16:23

0

Shortly:

const isEmpty = !Object.keys(jsonresp).length

answered Mar 14 '18 at 16:23

sultan

thanks for changing - almost downvoted :-) – Randy Casburn Mar 14 '18 at 16:26
@RandyCasburn hope it helped you :) – sultan Mar 14 '18 at 16:45
Your first answer didn't help because it was blatantly wrong!! But you edited and corrected it...so all it good. – Randy Casburn Mar 14 '18 at 16:50

score 0 · Accepted Answer · answered Mar 14 '18 at 16:26

0

You can use Object.keys() function to get keys of the object as an array and then check the array to see whether it is empty.

var obj = {};
var arr = Object.keys(obj);
console.log(arr);
console.log("Is Empty : " + (arr.length == 0));

answered Mar 14 '18 at 16:26

3 Answers3