missing key and values in Objects in Javascript

I’m JavaScript beginner.

I got one Object from an API like

data= {
key1: “v1”
key2: “v2”
key3: “v3”
}

the above value is returned when I debug it like

console.log(data), 

I wanna use v3 value, but when I tried to get it like below, “Undefined” came. expected result is “v3”

var v3 = data.key3;

am able to get v1 and v2 values, but v3 failed.
Also, if i debug it like

console.log(JSON.stringfy(data));

the returned value is

{key1: "v1"
    key2: "v2"}

I am wondering why thiskind of missing key and value is occuring..
If you have any suggestions, please let me know it.

Thanks