如何在JavaScript中调用原型之外的函数？

在

TopDownGame

的范围之外，如何调用

setTile

函数？我尝试了

topdownggame.Lesson31.setTile（x，y）

，但不起作用

var TopDownGame = TopDownGame || {};

TopDownGame.Lesson31 = function() {};

TopDownGame.Lesson31.prototype = {
    setTile: function(x, y) {
        console.log(tile);
    }
};

---

如果已添加到原型，则必须创建对象的实例以调用方法：

var TopDownGame = TopDownGame || {};

TopDownGame.Lesson31 = function() {};
TopDownGame.Lesson31.prototype = {

setTile: function(x, y) {
        console.log("setTile invoked");
    },
};


var instance = new TopDownGame.Lesson31();
instance.setTile(3, 4);

您试图调用它，就像它是一个静态方法一样。如果这是您真正想要做的，那么将方法定义为函数的属性，而不是原型的属性

TopDownGame.Lesson31 = function() {};
TopDownGame.Lesson31.staticMethod = function() {
    console.log('Static method invoked');
}

TopDownGame.Lesson31.staticMethod();

但是，如果您确实希望保留

setTile

作为原型方法，但仍要调用它，则可以使用

apply

方法

var TopDownGame = TopDownGame || {};

TopDownGame.Lesson31 = function() {};
TopDownGame.Lesson31.prototype = {
    setTile: function(x, y) {
        console.log(`setTile invoked, this='${this}', x=${x}, y=${y}`);
    },
};

new TopDownGame.Lesson31().setTile(3, 4);
TopDownGame.prototype.setTile.apply('actually a string', [5, 6]);

这将导致：

setTile invoked, this='[object Object]', x=3, y=4
setTile invoked, this='actually a string', x=5, y=7

---

如果已添加到原型，则必须创建对象的实例以调用方法：

var TopDownGame = TopDownGame || {};

TopDownGame.Lesson31 = function() {};
TopDownGame.Lesson31.prototype = {

setTile: function(x, y) {
        console.log("setTile invoked");
    },
};


var instance = new TopDownGame.Lesson31();
instance.setTile(3, 4);

您试图调用它，就像它是一个静态方法一样。如果这是您真正想要做的，那么将方法定义为函数的属性，而不是原型的属性

TopDownGame.Lesson31 = function() {};
TopDownGame.Lesson31.staticMethod = function() {
    console.log('Static method invoked');
}

TopDownGame.Lesson31.staticMethod();

但是，如果您确实希望保留

setTile

作为原型方法，但仍要调用它，则可以使用

apply

方法

var TopDownGame = TopDownGame || {};

TopDownGame.Lesson31 = function() {};
TopDownGame.Lesson31.prototype = {
    setTile: function(x, y) {
        console.log(`setTile invoked, this='${this}', x=${x}, y=${y}`);
    },
};

new TopDownGame.Lesson31().setTile(3, 4);
TopDownGame.prototype.setTile.apply('actually a string', [5, 6]);

这将导致：

setTile invoked, this='[object Object]', x=3, y=4
setTile invoked, this='actually a string', x=5, y=7

---

var topdownggame=topdownggame | |{}；Lesson31={setTile:function（x，y）{console.log（tile）；}，}；var topdownggame=topdownggame | |{}；Lesson31={setTile:function（x，y）{console.log（tile）；}，}；