Typescript全局变量

发布于12月11日

有没有一种方便的方法可以在模块内访问全局变量，而不会出现编译器错误，比如下面使用的CANVAS_WIDTH？

    export class Bullet {


        x: number = 22;
        y: number = 22;

        constructor (speed: number) {
            this.xVelocity = speed;
        }

        inBounds() {
            return this.x >= 0 && this.x <= CANVAS_WIDTH &&
                this.y >= 0 && this.y <= CANVAS_HEIGHT;
        };
}
}

推荐答案

你需要将这些属性定义为静态的，然后你可以像这样轻松地访问它，

export class Game {
    static canvas: JQuery;
    static CANVAS_WIDTH: number;
    static CANVAS_HEIGHT: number;
    bullet: Bullet;

    constructor(canvasElem: JQuery) {
        Game.canvas = canvasElem;
        Game.CANVAS_WIDTH = Game.canvas.width();
        Game.CANVAS_HEIGHT = Game.canvas.height();
    }
}

export class Bullet {
    x: number = 22;
    y: number = 22;

    public inBounds() {
        // accessing static properties
        return this.x >= 0 && this.x <= Game.CANVAS_WIDTH && this.y >= 0 && this.y <= Game.CANVAS_HEIGHT;
    }
}

这将编译为:

define(["require", "exports"], function(require, exports) {
    var Game = (function () {
        function Game(canvasElem) {
            Game.canvas = canvasElem;
            Game.CANVAS_WIDTH = Game.canvas.width();
            Game.CANVAS_HEIGHT = Game.canvas.height();
        }
        return Game;
    })();
    exports.Game = Game;

    var Bullet = (function () {
        function Bullet() {
            this.x = 22;
            this.y = 22;
        }
        Bullet.prototype.inBounds = function () {
            // accessing static properties
            return this.x >= 0 && this.x <= Game.CANVAS_WIDTH && this.y >= 0 && this.y <= Game.CANVAS_HEIGHT;
        };
        return Bullet;
    })();
    exports.Bullet = Bullet;
});
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