FunctionCallbackInfo: This, Holder and Callee.

[Jane Chen]

What's the difference between This() and Holder() in FunctionCallbackInfo?  What does Callee() return?  Can you show it with a JavaScript example?

Thanks!

[Ben Noordhuis]

On Fri, Sep 12, 2014 at 6:25 AM, Jane Chen <jxch...@gmail.com> wrote:
> What's the difference between This() and Holder() in FunctionCallbackInfo?
> What does Callee() return? Can you show it with a JavaScript example?

.Callee() is the JS function that called your API function. It's
equivalent to the (deprecated) arguments.callee property.

.This() and .Holder() are often identical. The only time (that I know
of) when they are different is when instantiating objects that have a
prototypical inheritance chain:

function F() {}
F.prototype = g;
var f = new F;
f.x = 42;

Assume |g| is instantiated from an ObjectTemplate with a setter for
|x|. The last line invokes the setter with .This() pointing to |f|
and .Holder() pointing to |g|.

[Mike Schwartz]

Callee is the "currently executing function" according to JavaScript 1.2 / ECMA 3

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/arguments/callee

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