对于 AMD 模块，什么时候（或为什么）可以在 Define() 中使用 require() ？

发布于 2024-12-11 03:43:30 字数 583 浏览 0 评论 0原文

我对AMD模块（例如使用RequireJs或curl.js）的理解是：

require()用于异步加载不同的模块，加载后执行回调fn。

要定义一个模块，您将有单独的脚本使用 define()

但我看到一些模块在其函数定义中使用 require() ，例如

define([a, b, c], function(i, ii, iii){ 
    require([d, e, f], function(d, e, f) {
        // do some stuff with these require()'d dependancies
    })
    /* rest of the code for this module */ 
})

但我发现这令人困惑，因为我认为如果一个模块具有依赖项，那么它们应该通过主 define([dependancies], fnDefinition) 函数传递，而不是通过 require()< /code> 按照上面的例子正在做。

这背后有原因吗？

原文

My understanding of AMD modules (using for example RequireJs or curl.js) is:

require() is used to asynchronously load different modules and when loaded then the callback fn is executed.

And to define a module, you would have separate scripts that use define()

But I've seen some modules use require() inside their function definition, e.g.

define([a, b, c], function(i, ii, iii){ 
    require([d, e, f], function(d, e, f) {
        // do some stuff with these require()'d dependancies
    })
    /* rest of the code for this module */ 
})

But I find this confusing because I would have thought that if a module has dependancies then they should be passed through via the main define([dependancies], fnDefinition) function and not within it via require() as per the above example is doing.

Is there a reasoning behind this?

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

那伤。 2024-12-18 03:43:30

您可能出于多种原因想要在模块中使用 require()。

但首先，请确保您请求引用正确的 require 变量。在您的示例中，对 require 的引用是全局。您需要引用一个 require ，其范围仅限于您的模块的上下文（有时称为“本地 require”）。这很简单：

define(["a", "b", "c", "require"], function(i, ii, iii, require){ 
    require(["d", "e", "f"], function(moduleD, moduleE, moduleF) {
        // do some stuff with these require()'d dependencies
    })
    /* rest of the code for this module */ 
});

这很重要的主要原因是确保正确解析相对模块 ID（例如“./peerModule”或“../unclePath/cousinModule”）。（这是原因之一，curl.js 默认没有全局 require。）

使用本地 require 的原因：

你不知道哪些模块由于运行时条件，在构建时（或加载时）需要
您明确希望推迟某些模块的加载，直到需要它们为止
您希望根据功能检测的结果加载模块的变体（尽管类似dojo 的“has!”插件可能是一个更好的解决方案（抱歉，链接让我困惑））

最后，AMD 定义了 require 的第二种用法，以与 CommonJS Modules/1.1 中编写的模块兼容，然后将其包装在 define 中。这些看起来像这样：

define(function(require, exports, module){ 
    var a = require("pkgZ/moduleA"), // dependency
        b = require("pkgZ/moduleB"); // dependency
    /* rest of the code for this module */ 
});

服务器端 javascript 开发人员可能会发现这种格式很有吸引力。 :)

一些 AMD 加载器（例如 RequireJS 0.2+、dojo 1.7+、bdLoad 和curl.js 0.6+）将检测这种混合 AMD/CJSM1.1 格式，并通过扫描模块中的 require 来电。

There are a few reasons you may want to use require() in a module.

But first, be sure you request a reference to the correct require variable. In your example, the reference to require is a global. You want a reference to a require that is scoped to the context of your module (sometimes called a "local require"). This is easy:

define(["a", "b", "c", "require"], function(i, ii, iii, require){ 
    require(["d", "e", "f"], function(moduleD, moduleE, moduleF) {
        // do some stuff with these require()'d dependencies
    })
    /* rest of the code for this module */ 
});

The main reason this is important is to ensure that relative module ids (e.g. "./peerModule" or "../unclePath/cousinModule") are resolved correctly. (This is one of the reasons, curl.js doesn't have a global require by default.)

Reasons to use a local require:

you don't know which modules are needed at build time (or at load time) due to run-time conditions
you explicitly want to defer loading of some modules until they're needed
you want to load a variation of a module based on results of feature detection (although something like dojo's "has!" plugin might be a better solution ( sorry, link eluding me))

Lastly, AMD defines a second usage of require for compatibility with modules authored in the CommonJS Modules/1.1 which are then wrapped in a define. These look like this:

define(function(require, exports, module){ 
    var a = require("pkgZ/moduleA"), // dependency
        b = require("pkgZ/moduleB"); // dependency
    /* rest of the code for this module */ 
});

Server-side javascript devs may find this format appealing. :)

Some AMD loaders (such as RequireJS 0.2+, dojo 1.7+, bdLoad, and curl.js 0.6+) will detect this hybrid AMD/CJSM1.1 format and find dependencies by scanning the module for require calls.

回复收藏 0 原文

~没有更多了~