Get all keys of a deep object in Javascript

You can do this by recursively traversing the object:

function getDeepKeys(obj) {
    var keys = [];
    for(var key in obj) {
        keys.push(key);
        if(typeof obj[key] === "object") {
            var subkeys = getDeepKeys(obj[key]);
            keys = keys.concat(subkeys.map(function(subkey) {
                return key + "." + subkey;
            }));
        }
    }
    return keys;
}

Running getDeepKeys(abc) on the object in your question will return the following array:

["1", "2", "3", "4", "5", "5.test", "5.tester", "5.tester.name", "count", "counter", "counter.count"]

I know this is bit old post...

This code covers all criteria in JSON object format like just object,object array, nested array object,nested object with array object etc.

getDeepKeys = function (obj) {
  var keys = [];
    for(var key in obj) {
        if(typeof obj[key] === "object" && !Array.isArray(obj[key])) {
            var subkeys = getDeepKeys(obj[key]);
            keys = keys.concat(subkeys.map(function(subkey) {
                return key + "." + subkey;
            }));
        } else if(Array.isArray(obj[key])) {
            for(var i=0;i<obj[key].length;i++){
               var subkeys = getDeepKeys(obj[key][i]);
               keys = keys.concat(subkeys.map(function(subkey) {
                return key + "[" + i + "]" + "." + subkey;
               }));
            }
        } else {
          keys.push(key);
        }
    }
    return keys;
}

Smaller version, no side effect, just 1 line in function body:

function objectDeepKeys(obj){
  return Object.keys(obj).filter(key => obj[key] instanceof Object).map(key => objectDeepKeys(obj[key]).map(k => `${key}.${k}`)).reduce((x, y) => x.concat(y), Object.keys(obj))
}

var abc = {
    1: "Raggruppamento a 1",
    2: "Raggruppamento a 2",
    3: "Raggruppamento a 3",
    4: "Raggruppamento a 4",
    count: '3',
    counter: {
        count: '3',
    },
    5: {
        test: "Raggruppamento a 1",

        tester: {
            name: "Ross"
        }
    }
};

function objectDeepKeys(obj){
  return Object.keys(obj)
    .filter(key => obj[key] instanceof Object)
    .map(key => objectDeepKeys(obj[key]).map(k => `${key}.${k}`))
    .reduce((x, y) => x.concat(y), Object.keys(obj))
}

console.log(objectDeepKeys(abc))