javascript - “使用常规函数'this'表示调用该函数的对象”是什么意思？

在解释箭头功能时，w3schools说：“在常规功能中，此关键字代表调用该函数的对象，可以是窗口，文档，按钮或其他任何东西”，而“在常规功能中，此关键字代表具有以下功能的对象：调用函数”。链接：https：//www.w3schools.com/js/js_arrow_function.asp

I'm trying to understand this sentence, not in relation to arrow functions but by itself. It seems that many other sources I found on the net contradict to this, saying that when a function gets called on its own (not as a method), 'this' gets bound to either the toplevel object (e.g. window) or undefined, depending on strict mode.

So I built a simple example (running non-strict in the browser). I did not want to use the examples from the w3schools site because they use event handlers for explanation, and I want to make sure that I avoid any additional binding logic that event handlers introduce.

<script type="text/javascript">

function foo() {
    console.log('foo on ' + this.prop);
}

function bar() {
    console.log('bar on ' + this.prop);
    var f = this.foo;
    f();
}

var x = {
    prop: 'x'
};
window.prop = 'w';

x.foo = foo;
x.bar = bar;
x.bar();

</script>

This logs: "bar on x" and "foo on w", which seems to indicate that in foo, this refers to the window. So obviously the w3schools explanation does NOT refer to an automatic binding of foo's this to bar's this when foo gets called inside bar. But what else does it mean?

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