Inject variable into callback function scope

问题

Is this possible to add variable to callback scope? What I want to achieve is:

...
Foo.prototype.bar = function(fn) {
    var baz = "baz!";
    fn.call(this);
}
...

Foo.bar(function() {
    console.log(baz) // gives "baz!"
});

I know I can pass baz variable as an argument or this but I'm interested in something like above.

回答1:

No, it's not possible. The only ways are the ones you pointed out: as an argument or in this.

回答2:

What about doing it this way:

var Foo = function(){}
Foo.prototype.handle = function(fn) {
    var baz = "baz !";
    eval('(' + fn.toString() + ')();');
}

var foo = new Foo;
foo.handle(function (){
    console.log(baz);
});

来源：https://stackoverflow.com/questions/8626951/inject-variable-into-callback-function-scope