is-pojo

Installation

npm install is-pojo

Usage

var isPojo = require("is-pojo");
isPojo({}) // true

// anything besides an absolutely plain object will return false.

// here are examples from the tests:

function Foo () {}
function Bar () {}
Bar.prototype.constructor = Object;

isPojo(function () {}) // false
isPojo([]) // false
isPojo(new Date()) // false
isPojo(true); // false
isPojo("abc"); // false
isPojo(123); // false
isPojo(new RegExp()); // false
isPojo(null); // false
isPojo(undefined); // false
isPojo(Object.create({})); // false
isPojo(new Foo()); // false
isPojo(new Bar()); // false
isPojo({constructor: Foo}); // true

Why?

The other module on npm that I found to do this checks an object's constructor property against Object. This approach is error-prone since there's nothing special about the constructor property; you can set it willy-nilly (see example above).

In contrast, an object's prototype can be set just once, at instantiation time. As such it's safe to check an object's prototype (obtained with Object.getPrototypeOf) against Object.prototype.