javascript - 如何在不同的函数中使用变量？

Question

我正在尝试在下面的 JavaScript 中打印出纬度 (lat) 变量。

如何引用 lat 变量？ this.lat、that.lat、neighborhood.lat 等？

在我的 javascript 中我有

var Vicinity = function (pubReference, sessionId, done, err) {
    this.ad = {
        getBannerHtml: function () {
            console.log(this.lat); // how do I refer to the lat variable?
        }
    };

    this.init = function (done, err) {
        var that = this;
        this.getLatLng(that, function (position) {
            that.lat = position.coords.latitude;
        }, err);
        if (typeof done === 'function')
            done(this);
    };

    this.init(done, err);
};

$(document).ready(function () {
    var data = new Vicinity(pubReference, sessionId,
        function (result) {
            $("#sticky").html(result.ad.getBannerHtml());
        }
    );
});

Answer 1

你就快到了。您已经在 init() 中将 that 声明为 this。只要在整个函数中这样做，它就应该起作用:

var Vicinity = function (pubReference, sessionId, done, err) {
    var that = this;
    this.ad = {
        getBannerHtml: function () {
            console.log(that.lat); // how do I refer to the lat variable?
        }
    };

    this.init = function (done, err) {
        var that = this;
        this.getLatLng(that, function (position) {
            that.lat = position.coords.latitude;
        }, err);
        if (typeof done === 'function')
            done(this);
    };

    this.init(done, err);
};

$(document).ready(function () {
    var data = new Vicinity(pubReference, sessionId,
        function (result) {
            $("#sticky").html(result.ad.getBannerHtml());
        }
    );
});