Lightswitch HTML全局JS文件传递变量 [英] Lightswitch HTML global JS file to pass variable

问题描述

我知道这在C#中是如何工作的，但是在javascript中却不是很多，所以我希望它是相似的.

我可以使用Javascript创建带有变量(var defaultValue = "1234")的master.js，我可以在与该项目相关的所有其他javascript文件中引用该变量吗?

因此就Lightswitch HTML而言，每个屏幕都具有一个js文件的能力，并且在屏幕上我希望能够检索此defaultValue.

1. 可以做到吗?
2. 如果是，如何在当前屏幕上获取此值?

到目前为止，我已经创建了一个main.js文件，并添加了以下功能:

function getDefaultValue(value) {

    var value = "1234";

    return value;
}

并在default.htm文件中声明了js文件:

<script type="text/javascript" src="Scripts/main.js"></script>

我知道这是我使用其他JavaScript文件的方式，例如blob.js，lsWires.js等...

在screen.js中使用此方法不起作用，因此这些阶段之一正在导致错误...

window.alert(main.getDefaultValue(value));

理想情况下，我想使用此默认值来设置值，即var test = main.getDefaultValue(value)

解决方案

当然可以，并且您在default.htm中使用的脚本声明似乎正确.

但是，当您描述的方法创建一个全局getDefaultValue函数(添加到全局窗口对象上下文中)时，您将不会像在c#中那样指定主命名空间"前缀.

您可以在LightSwitch屏幕中使用以下方法，而不是使用main.getDefaultValue调用函数:

myapp.BrowseProducts.created = function (screen) {
    window.alert(window.getDefaultValue("123")); // This will display 1234

    // As window is a global object, its window prefix can be omitted e.g.
    alert(getDefaultValue("123")); // This will display 1234
};

或者，如果您想在main.js中定义一个全局defaultValue变量(可能是您要实现的方法)，则main.js文件中将包含以下代码:

var defaultValue = "5678";

然后，您将在LightSwitch屏幕中按以下方式访问它:

myapp.BrowseProducts.created = function (screen) {
    alert(defaultValue); // This will display 5678
    defaultValue = "Hello World";
    alert(defaultValue); // This will now display Hello World
};

此外，如果您想在主命名空间"中组织函数/属性，则可以在main.js文件中使用以下类型的方法:-

var main = (function (ns) {

    ns.getDefaultValue = function (value) {
        var value = "1234";
        return value;
    };

    ns.defaultValue = "5678";

    return ns;
})(main || {});

然后在LightSwitch屏幕中将这些调用如下:-

myapp.BrowseProducts.created = function (screen) {
    alert(main.getDefaultValue("123")); // This will display 1234
    alert(main.defaultValue); // This will display 5678
    main.defaultValue = "Hello World";
    alert(main.defaultValue); // This will now display Hello World
};

以下帖子介绍了这种方法:-

如何将javascript名称空间跨多个文件?

JavaScript模块模式:深入

I know how this works in C#, however not so much in javascript so I am hoping it is similar.

With Javascript can I create say a master.js, with a variable (var defaultValue = "1234"), which I can reference in all other javascript files associated with the project?

so in terms of Lightswitch HTML, each screen has the ability to have a js file, and on the screen I want to be able to retrieve this defaultValue.

1. Can this be done?
2. If yes, how can I get this value onto the current screen?

so far I have created a main.js file, added this function:

function getDefaultValue(value) {

    var value = "1234";

    return value;
}

and declared the js file in the default.htm file:

<script type="text/javascript" src="Scripts/main.js"></script>

I know this is how i am using other JavaScript files like blob.js, lsWires.js etc...

using this method in by screen.js doesn't work so one of these stages is causing an error...

window.alert(main.getDefaultValue(value));

ideally i would like to use this defaultvalue for setting a value, i.e. var test = main.getDefaultValue(value)

解决方案

This is certainly possible, and the script declaration you've used in your default.htm appears correct.

However, as the approach you've described creates a global getDefaultValue function (added to the global window object context) you wouldn't specify a main 'namespace' prefix like you would in c#.

Instead, rather than calling the function using main.getDefaultValue, you'd use the the following approach within your LightSwitch screens:

myapp.BrowseProducts.created = function (screen) {
    window.alert(window.getDefaultValue("123")); // This will display 1234

    // As window is a global object, its window prefix can be omitted e.g.
    alert(getDefaultValue("123")); // This will display 1234
};

Or, if you want to define a global defaultValue variable in your main.js (probably the approach you're looking to implement) you would have the following code in your main.js file:

var defaultValue = "5678";

Then you'd access it as follows in your LightSwitch screens:

myapp.BrowseProducts.created = function (screen) {
    alert(defaultValue); // This will display 5678
    defaultValue = "Hello World";
    alert(defaultValue); // This will now display Hello World
};

Also, if you'd like to organise your functions/properties in a main 'namespace', you could use the following type of approach in your main.js file: -

var main = (function (ns) {

    ns.getDefaultValue = function (value) {
        var value = "1234";
        return value;
    };

    ns.defaultValue = "5678";

    return ns;
})(main || {});

These would then be called as follows in your LightSwitch screens: -

myapp.BrowseProducts.created = function (screen) {
    alert(main.getDefaultValue("123")); // This will display 1234
    alert(main.defaultValue); // This will display 5678
    main.defaultValue = "Hello World";
    alert(main.defaultValue); // This will now display Hello World
};

This type of approach is covered in the following posts: -

How to span javascript namespace across multiple files?

JavaScript Module Pattern: In-Depth

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