JavaScript Emptiness

This [].isEmpty() // true is easier to read than [].length === 0 // true

But if you try that you will get an error saying Uncaught TypeError: [].isEmpty is not a function

You can easily prototype this behavior.

Arrays

Array.prototype.isEmpty = function () {
  return this.length === 0;
};

// Examples

[].isEmpty(); // true

const a = [];
a.isEmpty(); // true

Strings

String.prototype.isEmpty = function () {
  return this.length === 0;
};

// Examples

"".isEmpty(); // true

const s = "";
s.isEmpty(); // true

Objects

{}.isEmpty() wont work but it does if you define an object first.

Object.prototype.isEmpty = function () {
  return Object.keys(this).length === 0;
};

Will work if you first define an object.

// Examples

const o = {};
o.isEmpty(); // true

Conclusion

Let's sum this up with a little "file" you can use

// isEmpty.js

Array.prototype.isEmpty = function () {
  return this.length === 0;
};

String.prototype.isEmpty = function () {
  return this.length === 0;
};

Object.prototype.isEmpty = function () {
  return Object.keys(this).length === 0;
};