TypeScript关闭范围错误：该名称在当前范围中不存在

Question

does anyone know why test1 fails to compile?

class Y { public myMethod: any; };
class QQ { public test(name, fun: () => any) { } }

var qq = new QQ();
qq.test("Run test1", () => {

        var outer = 10;

        Y.prototype.myMethod = () => {

          // Error: The name 'outer' does not exist in the current scope
            outer = 11;
        }
});

But the following works:

   qq.test("Run test2", () => {

            var outer = 10;
            var fun = ()=> { outer = 11; };

            Y.prototype.myMethod = fun;
    });

The JavaScript version of the required code would look look like this:

qq.test("Run test1", function () {
    var outer = 10;

    Y.prototype.myMethod = function () {
        outer = 11;
    };
});

The outer function declares a variable "outer" within its closure, which should naturally be visible to the inner function.

Answer 1

Shortened to just the salient points:

This is the JavaScript I think you are expecting.

var Y = (function () {
    function Y() { }
    Y.prototype.myMethod = function () {
    };
    return Y;
})();
var QQ = (function () {
    function QQ() { }
    QQ.prototype.test = function (name, fun) {
        fun();
    };
    return QQ;
})();
var qq = new QQ();
qq.test("Run test1", function () {
    var _this = this;
    _this.outer = 10;
    Y.prototype.myMethod = function () {
        alert(_this.outer);
    };
});
var y = new Y();
y.myMethod();

You need to change your TypeScript to get this output:

class Y { 
    public myMethod() {

    }
}

class QQ {
    public test(name, fun: () => any) { // updated signature
        fun(); // call the function
    }
}

var qq = new QQ();

qq.test("Run test1", () => {
        this.outer = 10; // use this.
        Y.prototype.myMethod = () => {
            alert(this.outer);
        }
});

var y = new Y();
y.myMethod();

And yes, TypeScript believes this.outer to be a problem in the alert statement, but compiles the correct JavaScript anyway. You can raise that as a bug at http://typescript.codeplex.com .

Answer 2

这是TypeScript中的一个错误，直到版本0.8.2 才被修复 。