chai expect to be a number code example

Example 1: chai expect type to be integer

var expect = require('chai').expect

expect(foo).to.be.a('number')
expect(foo % 1).to.equal(0)

Example 2: what does chai expect return

Object.prototype.b = 2;

expect({a: 1}).to.have.own.property('a');
expect({a: 1}).to.have.property('b');
expect({a: 1}).to.not.have.own.property('b');

expect({a: 1}).to.own.include({a: 1});
expect({a: 1}).to.include({b: 2}).but.not.own.include({b: 2});