typeof（/ \\ s /）和$ .type（/ \\ s /）之间的区别

Question

I don't understand why it's throwing message object when I try:

 alert(typeof(/\\s/)) 

To check again, I've made a change:

 alert($.type(/\\s/)) 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 

We've got regexp now.

So, my question: why is typeof(/\\s/) an object instead of string or regexp in javascript?

Answer 1

A regular expression is an "object" because it's an object, just like Date, etc. A regular expression is an object that describes a pattern of characters.

If you use typeof with an object , you get "object"

Some other examples:

typeof []; // "object"
typeof null; // "object"
typeof /regex/ // "object"
typeof new String(""); // "object"

With $.type

If the argument is either a primitive value or an instance of a standard built-in ECMAScript object, the [[Class]] internal property is used to determine the type.

Example:

jQuery.type( /test/ ) === "regexp"

Documentation on $.type