load.md

load

Module Exports

'isPlugin'

Tests a value to determine whether is a plugin (an object with a load method).

import { isPlugin } from '@dojo/core/load';

// true
isPlugin({
	load() {}
	normalize() {}
});

isPlugin(1); // false
isPlugin([]); // false
isPlugin([]); // false
// false
isPlugin({
	observer() {}
});

'load'

Dynamically loads a module or other resource.

import load, { useDefault } from '@dojo/core/load';

// Load a single module
load('mymodule').then(([ myModule ]: [ any ]) => {
	// ...
});

// Load multiple modules
load('namespace/first', 'namespace/second').then(([ first, second ]: [ any, any ]) => {
	// ...
});

// Load modules with relative ids as relative to the current module
load(require, './first', './second').then(([ first, second ]: [ any, any ]) => {
	// ...
});

// Automatically map modules to their default export
load('namespace/first').then(useDefault).then(([ first ]: [ any ]) => {
	// ...
});

// Load a custom resource via a plugin
load(require, 'plugin!./template.html').then(([ html ]: [ string ]) => {
	// ...
});

Using Plugins

AMD-style plugins can be used with load by passing in module ids with the format {pluginId}!{resourceId}. First, the plugin will be loaded, and then the resource id (the string that follows the ! in the mid passed to core/load) will be normalized and passed to the plugin's load method. If the plugin module does not actually have a load method, then the resource id is ignored, and the module is returned as-is. Plugins can also expose an optional normalize method that is passed the resource id and a resolver method (which will be either require.toUrl, require.resolve, or an identity function, depending on the environment). Note that if no normalize method is provided, then the provided resource id will be resolved using require.toUrl or require.resolve, depending on the environment. Again, if the plugin module has a default export, the normalize method MUST exist on that object.

Note: the plugins that can be used with load loosely follow the amdjs plugin API, with the following exceptions:

1. The plugin's load method does not receive a contextual require or a configuration object.
2. Rather than execute a callback when the resource has loaded, the plugin's load method instead must return a promise that resolves to that resource.

// Plugin that does not use the default export.
import { Load } from '@dojo/core/load';

export function normalize(resourceId: string, resolver: (id: string) => string): string {
	return resolver(resourceId);
}

export function load(resourceId: string, load: Load) {
	// This plugin does nothing more than load the resource id with `core/load`.
	return load(resourceId);
}

// The same plugin, but using the default export
import { Load } from '@dojo/core/load';

const plugin = {
	normalize(resourceId: string, resolver: (id: string) => string): string {
		return resolver(resourceId);
	},

	load(resourceId: string, load: Load) {
		// This plugin does nothing more than load the resource id with `core/load`.
		return load(resourceId);
	}
};
export default plugin;

import load from '@dojo/core/load';

// 1. The module with the id `plugin` is loaded.
// 2. If `plugin` is not actually a plugin, then `plugin` itself is returned.
// 3. If the plugin has a normalize method, then "some/resource/id" is passed to it,
//    and the return value is used as the resource id.
// 4. The resource id is passed to the plugin's `load` method.
// 5. The loaded resource is used to resolve the `load` promise.
load('plugin!some/resource/id').then(([ resource ]: [ any ]) => {
	// ...
});