为什么`window.console.log（this）`不记录控制台对象？

Question

I'm just getting into advanced contextual instantiation, using prototype chain etc.

I'm curious how the window.console object is created such that the function log thinks it's context is the window instance, not the console. Is this something to do with Object.create the new keyword, or binding / self = this?

window.console has a constructor (Console) and I'm curious what the cleanest way to invoke the constructor, passing Window instance/context would be? Pass it in as a param?? If Console is a seperate constructor, I think Window would be the one constructing it with a new context, rather than saying

windowInstance.console.log = function (args) {

}.bind(windowInstance, args);

Pretty much, I'm imagining a layout like this, but don't understand how this gets routed

var window = new Window();
window.console.log(this); // logs window

function Window () {
    // this === window when constructed above
    this.console = new Console();
}

function Console () {
    this.log = function () {} // where this === window.console but log thinks it's window
}

Thanks

Answer 1

If you had:

var obj = { hello: "world" };
console.log(obj);

would you be surprised that the console showed that object? Well by the same token,

console.log(this);

logs the value of this as it is outside the call to the console function. You can't force console.log() to log what it thinks the value of this is in its own frame of reference; there's just no provision for that in the API (because frankly it's not very useful). If you want to log the state of the window.console object however you can:

console.log(window.console);