Is Function really an Object

Question

I am a self taught web developer and am still trying to come to grips with some JavaScript fundamentals. Below are some quotes extracted from Douglas Crockford\'s Good Part

Answer 1

If Function is an Object then why is its type a function and not object?

Because the typeof operator is defined like that, probably for usability:

• Object (native and does not implement [[Call]]) returns "object"
• Object (native or host and does implement [[Call]]) returns "function"
• Object (host and does not implement [[Call]]) returns an Implementation-defined value that may not be "undefined", "boolean", "number", or "string".

[[Call]] is an internal property of an object that identifies the object as a function (callable). A non-native object is an object provided by the host (e.g. browser), such as a DOM object or an instance of ActiveXObject.

puzzled so the constructor is in-fact a function?

Why wouldn't it be? Constructors are functions. Instances can only be constructed using functions. Object.constructor is a function, but it's also an object. See the following:

console.log((function () { }) instanceof Object);
//-> true

Also, from the ECMAScript speficiation:

Every built-in function and every built-in constructor has the Function prototype object, which is the initial value of the expression Function.prototype (15.3.4), as the value of its [[Prototype]] internal property.

Unless otherwise specified every built-in prototype object has the Object prototype object, which is the initial value of the expression Object.prototype (15.2.4), as the value of its [[Prototype]] internal property, except the Object prototype object itself.

And also, to answer your final puzzlement:

The Function prototype object is itself a Function object (its [[Class]] is "Function") that, when invoked, accepts any arguments and returns undefined.