Flatten an object recursively (Asked in Wingify Interview)

flatten.js

const flatten = function(inputObj) {
	var respObj = {};
	
	for (let i in inputObj) {
		if (!inputObj.hasOwnProperty(i)) continue;
		
		if ((typeof inputObj[i]) == 'object') {
			let flatObject = flatten(inputObj[i]);
			for (let x in flatObject) {
				if (!flatObject.hasOwnProperty(x)) continue;
				
				respObj[i + '.' + x] = flatObject[x];
			}
		} else {
			respObj[i] = inputObj[i];
		}
	}
	return respObj;
};

Write an implementation of a function called flatten that flattens a nested object. The method takes an object and returns a new flattened object.

Base structure:

function flatten(obj) {
 // should return a new flattened object.
}

For example:
For the given input object,

var inputObj = {
        'name': 'jane',
        'last_name': 'doe',
        'profession': 'engineer',
        'characteristics': {
                'intelligent': true,
                'punctual': false,
                'experience': {
                        '2012': 'college passout',
                        '2014': 'mba passout',
                        '2016': 'employed'
                }
        }
};

flatten(inputObj);

Output:

{
        'name': 'jane',
        'last_name': 'doe',
        'profession': 'engineer',
        'characteristics.intelligent': true,
        'characteristics.punctual': false,
        'characteristics.experience.2012': 'college passout',
        'characteristics.experience.2014': 'mba passout',
        'characteristics.experience.2016': 'employed'
}

Note: The method should NOT modify the original object. It should return a new object.