Ken Adeniji's Blog

To determine the type of an unevaluated operand

typeof undefined === "undefined"

typeof null === “object”

typeof true === “boolean”

typeof 3.14 === “number”

typeof “good” === “string”

typeof Infinity === “number”

typeof NaN === “number”

typeof new Date() === “object”

typeof {a:1} === ‘object’

typeof [1, 2, 4] === ‘object’; // use Array.isArray or Object.prototype.toString.call to differentiate regular objects from arrays

To differentiate between the various typeof objects

var toClass = {}.toString
console.log( toClass.call( [1, 2] ) );

To determine if an object, is an instance of a class

function Car(make, model, year) {
this.make = make;
this.model = model;
this.year = year;
}
var mycar = new Car("Honda", "Accord", 1998);
var a = mycar instanceof Car; // returns true
var b = mycar instanceof Object; // returns true
Reference

http://javascript.info

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof

Tags: JavaScript

This entry was posted on September 26, 2013 at 5:01 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.