Mastering SeaJS: A Quick Guide to CMD‑Based JavaScript Module Loading

SeaJS is a JavaScript module loader that follows the CMD specification, allowing modular development and loading in all mainstream browsers.

Getting Started Example

In an HTML page, load the initial module init.js. The init module calls module1, which in turn loads module2.

Module Definition

Modules are defined with the define function: define(id?, deps?, factory) Parameters:

id (optional): the module identifier; if omitted, the file’s absolute path is used.

deps (optional): an array of module dependencies.

factory (required): the factory function that creates the module.

Example:

define('hello', ['jquery'], function(require, exports, module) {
    // module code
});

Factory Function

The factory function receives three arguments: require: loads dependent modules. exports: an object on which the module’s public API is attached. module: metadata about the module, including module.id, module.dependencies, and module.exports (which is the same object as exports).

Module Addressing

SeaJS supports three addressing styles:

Absolute address : a full URL, e.g., require("http://example/js/a").

Relative address : a path relative to the file containing the require call, e.g., require("../a") to load a.js from a sibling directory.

Base address : when the path is neither absolute nor starts with “./”, SeaJS resolves it against the global base configuration.