How can I check if a JSON is empty in NodeJS?

Question

How can I check if a JSON is empty in NodeJS?

I have a function that checks to see whether or not a request has any queries, and does different actions based off that. Currently, I have if(query) do this else something else. However, it seems that when there is no query data, I end up with a {} JSON object. As such, I need to replace if(query) with if(query.isEmpty()) or something of that sort. Can anybody explain how I could go about doing this in NodeJS? Does the V8 JSON object have any functionality of this sort?

javascript
json
node.js
v8

Answer 1

You can use either of these functions:

// This should work in node.js and other ES5 compliant implementations.
function isEmptyObject(obj) {
  return !Object.keys(obj).length;
}

// This should work both there and elsewhere.
function isEmptyObject(obj) {
  for (var key in obj) {
    if (Object.prototype.hasOwnProperty.call(obj, key)) {
      return false;
    }
  }
  return true;
}

Example usage:

if (isEmptyObject(query)) {
  // There are no queries.
} else {
  // There is at least one query,
  // or at least the query object is not empty.
}

Answer 2

You can use this:

var isEmpty = function(obj) {
  return Object.keys(obj).length === 0;
}

or this:

function isEmpty(obj) {
    return !Object.keys(obj).length > 0;
}

You can also use this:

function isEmpty(obj) {
    for(var prop in obj) {
        if(obj.hasOwnProperty(prop))
            return false;
    }

    return true;
}

If using underscore or jquery, you can use their isEmpty or isEmptyObject calls.

Answer 3

late in the game, but I am using another way which I like more even if it is not "proper" solution.

JSON.stringify(obj) === '{}'

I know this approach might get bad reviews because I am assuming that string representation of empty object is {} ( and what if it was { } ) - but I find it easier this way without a function and it seems to work fine for me.