Javascript: Getting all existing keys in a JSON array

Question

I have a JSON array like below:

var jsonArray = [{"k1":"v1"},{"k2":"v2"},{"k3":"v3"},{"k4":"v4"},{"k5":"v5"}]

I don't know which keys does exists in this array. I want to get all the existing key from the array.

It should be possible something like this:

for(i=0;i<jsonArray.lenght;i++){
  // something like-  key = jsonArray[i].key
  // alert(key);
}

Please tell me the method or way to get all keys existing in Json array.

Regards

Answer 1

Why don't you use a

var jsonObject = {"k1":"v1","k2":"v2","k3":"v3","k4":"v4","k5":"v5"}

instead of your

var jsonArray = [{"k1":"v1"},{"k2":"v2"},{"k3":"v3"},{"k4":"v4"},{"k5":"v5"}]

? Then the solution would be so simple: Object.keys(jsonObject).

Answer 2

Try this:

var L = jsonArray.length;
for (var i = 0; i < L; i++) {
    var obj = jsonArray[i];
    for (var j in obj) {
        alert(j);
    }
}

I've also made some modifications of your current code (like length caching).