javascript - 如何在 TypeScript 中捕获 "this"

Question

我什至尝试包装到一个模块中，但仍然未能在所有尝试中捕获“this”。由以下 Typescript 生成的 Javascript 无法解析 this 并且无法返回所需的结果。我该如何解决 TypeScript 中的这个问题？

var secretNumberGame = () => {
    var secretNumber: number = 21;
    var counter: number = 9;
    return {
        responses: {
            equal: "You are correct! Answer is " + secretNumber,
            lower: "Too high!",
            higher: "Too low!"
        },
        guess: (guess: number) => {
            counter++;
            var key = (guess == secretNumber) ? "equal" : (
                (guess < secretNumber ? "higher" : "lower"));
            console.log(this.responses[key]);
            return counter;
        }
    }
}
var game = secretNumberGame();
console.log(game.guess(45));
console.log(game.guess(18))
console.log(game.guess(21));

Answer 1

请只使用函数而不是()=>:

var secretNumberGame = () => {
    var secretNumber: number = 21;
    var counter: number = 9;
    return {
        responses: {
            equal: "You are correct! Answer is " + secretNumber,
            lower: "Too high!",
            higher: "Too low!"
        },
        guess: function (guess: number) {
            counter++;
            var key = (guess == secretNumber) ? "equal" : (
                (guess < secretNumber ? "higher" : "lower"));
            console.log(this.responses[key]);
            return counter;
        }
    }
}
var game = secretNumberGame();
console.log(game.guess(45));
console.log(game.guess(18))
console.log(game.guess(21));

这里有一些关于粗箭头的文档:http://basarat.gitbooks.io/typescript/content/docs/arrow-functions.html