Bundling a reusable library with systemjs builder - javascript

My brain has melted trying to bundle code for a reusable library and I need someone to steer me back on the path.
I've written a library in TypeScript that I want to reuse in multiple projects using jspm.
It has a single entry point file called Index.js which exports just one class I want to expose (Class1).
Index.js
export { Class1 } from "./Classes/Class1";
The problem is that when I bundle this to a single file using systemjs-builder it dumps all of the dependencies in there.
Build output:
System.register("Classes/Class2.js", [], function(exports_1) {
});
System.register("Classes/Class1.js", ["Classes/Class2.js"], function(exports_1) {
});
System.register("Index.js", ["Classes/Class1.js"], function(exports_1) {
});
I don't believe an SFX bundle is suitable because I want to load this with systemjs, so there are a few things here I don't understand.
I don't want to expose class2 (it's just a dependency of class1) - but it looks to me from the output like anyone could just require it if they wanted to.
What about module ID clashes? What if I have another 3rd party library that also defines a Classes/Class1 module?
What I essentially want is a single file that exports only the modules I require and nothing else and is namespaced so that it doesn't clash with any other libraries. How can I achieve this?

Related

Use all files in a folder like a one big JS

Is it possible to configure ESLint in WebStorm so functions, variables, etc. are parsed also from files in the same folder? In my build process, I concatenate all files in the same folders into big closures, for example:
src/
main/ ===> "main.js"
api.js
init.js
ui.js
constants.js
.
.
renderer/ ===> "renderer.js"
core.js
events.js
I would like ESLint to treat all those files just like one, so I don't get "undef" errors for things that are defined.
If it can't be done automatically, I wouldn't mind to create a manual configuration specifying all those files if that is possible.
EDIT: Why I don't (can't) use modules? TLDR- legacy code and project requirements.
I need to minify all code. Current closure compiler can transpile ES6 into ES5, but I found some ES6 features very prone to produce broken code. So I am forced to use ES5.
As I need ES5. I would only be able to use require() to use modules. Now that's a problem, as require() is a dynamic include and it impacts performance on my context (big electron app for modest power devices)
So to answer #Avin_Kavish, I agree what I do is "technically non conforming", but at the end of the build process it is, because each folder has been grouped into a file. That file is the module or the script. To group the files I use a Gradle plugin https://github.com/eriwen/gradle-js-plugin, I inject a "closure header" and a "closure footer", and all the files in between in the order I want.
Despite the inconvenience, at the end I get super-compact nodeJS code, with all methods obfuscated, etc.
I ended up using #Patrick suggestion, thanks for that!
EDIT 2
WebPack + Electron-WebPack turned out to be what I was looking for.
BTW- I think the proper way to do this is if EsLint would allow a "folder" sourceType.
You didn't provide code examples in your question, but I assume you do something like this:
api.js
const api = {
fetchData() {
// some code that fetches data
}
};
core.js
const core = {
init() {
api.fetchData();
}
};
The ESLint rule that causes errors when you lint these JavaScript modules is the no-undef rule.
It checks for variables that are used without having been defined. In the code example core.js above, this would be api, because that is defined in another module, which ESLint doesn't know about.
You don't care about these errors, because in your actual JS bundle used in production, the code from api.js and core.js is concatenated in one bundle, so api will be defined.
So actually api in this example is a global variable.
The no-undef rule allows you to define global variables so that they won't cause errors.
There are two ways to do this:
Using Comments
At the beginning of your core.js module, add this line:
/* global api */
Using the ESLint Config
As explained here – add this to your .eslintrc file:
{
"globals": {
"api": "writable"
}
}
Side Note
As some commenters to your question pointed out, it would probably be better to use import and export statements in the modules, together with a module bundling tool like webpack to create one bundle from your JavaScript modules.
A physical JavaScript file with an import/export statement is a module by the standard. A single .js file without import/export is a script by the standard. What you are trying to do is non-conforming to this, there is no specification in ECMAScript that allows splitting a single script or module across several files. I do get where you are coming from, for example: C# has partial classes that allows you to split a class across multiple files. But trying to replicate this without a standard syntax is not wise. Especially, when import/export can and will do the job for you
For example, with the following assumptions, your main.js can be refactored to,
constants.js // <--- constants
ui.js // <--- logic to build UI
api.js // <--- exposing public api
init.js // <--- setup code before use
// main.js
// If you name this index.js you can import it as 'src/main' instead of 'src/main/main.js'
import { A,B } from './constants'
import { api } from './api'
import { displayUi } from './ui'
import { init } from './init'
init(A);
displayUi(B);
export { api } // <-- re-expose public api

Moving from Gulp/Grunt to Webpack for an AngularJs 1.x project

I have a two-year-old AngularJs 1.x project, which is built with Gulp for development and Grunt for production (don't ask me why; I don't know either).
The build process is basically:
Compile all scss files into one css file
Merge all JS files into one JS file. We are not using any import mechanism. Each file is basically one of AngularJs' controller, component, service or filter. Something like this:
angular.module("myApp").controller("myCtrl", function() {//...});
Merge all html templates into one JS file. Each template is hardcoded with $templateCache.
Moving assets like images and fonts into the build folder.
Moving third-party libraries into the build folder.
Now I want to switch to webpack for this project. I want to incrementally modernize this project, but the first step would be just building it with webpack with a similar process like the above. I would like to keep the code base as much the same as possible. I don't want to add import for all the JS files yet. There are too many. I would also like to add a babel-loader.
I have some basic concepts about webpack, but never really customized the configuration myself.
Would anyone please give me some pointers? Like which loaders/plugins would I need, etc.? Thanks!
My process to do such a transition was gradual, I had a similar Grunt configuration.
These are my notes & steps in-order to transition to Webpack stack.
The longest step was to refactor the code so it will use ES6 imports/exports (yeah, I know you have said that it is not a phase that you wanna make, but it is important to avoid hacks).
At the end each file looks like that:
//my-component.js
class MyComponentController { ... }
export const MyComponent = {
bindings: {...},
controller: MyComponentController,
template: `...`
}
//main.js
import {MyComponent} from 'my-component'
angular.module('my-module').component('myComponent', MyComponent);
In order not going over all the files and change them, we renamed all js files and added a suffix of .not_module.js.
Those files were the old untouched files.
We added grunt-webpack as a step to the old build system (based on Grunt).
It processed via Webpack all the new files (those that are without .not_module.js suffix).
That step produced only one bundle that contains all the files there were converted already, that file we have added to concat step.
One by one, each converted file gradually moved from being processed by Grunt tasks to be processed by Webpack.
You can take as a reference that webpack.config.
Good luck.

How to use js modules from non-module files

I'm a beginner at using js modules.
I'm working on a fairly simple web application. It uses typescript and angular 2, which heavily relies on modules.
Most of my app ts files 'import' one or many js modules (usually mostly angular 2 modules).
As I understand, because my app ts files have a top level 'import', they are automatically considered a js module by typescript.
However, I want any of my app ts files to be accessible by any other of my app ts files, without having to 'import' each other. But because they are now modules themselves, ts requires me to do that...
Is it possible?
It seems crazy to me that for each of my app ts file, I should have to declare every other of my app ts files that are used in there (I like to have tiny files with a single class/interface). In addition, this relies on relative paths which breaks as soon as I restructure my folder structure.
Am I thinking about this the wrong way?
You must have a js file which is an entry point to your application right?.. So in that file just import all the modules which you want to access without importing and attach them to the window object. Since the window object is available globally, you can access your module from anywhere without importing the corresponding module. For example,
Consider this scenario:
You have a module in a file called module1.ts
The entry point of your application is a file called index.ts
And you have a module2 where you require something from module1
// module1.ts
function add(first: number, second: number): number {
return first + second
}
export {add}
in your index.ts
// index.ts
import {add} from '<path to module1>/module1';
window.add = add
Now in your module2
// module2.ts
window.add(1, 2)
Since the window object is available globally you can attach as many properties to it as you like.
As far as the type resolution is concerned you can declare a window module with the add function you require in a .d.ts file as follows:
declare module window {
add: (first: number, second: number) => number
}
Declaring dependencies (e.g modules) for each file is a double-edged sword.
The advantage is that there is no 'magic' - you know exactly where each function, variable, class etc. is coming from. This makes it much easier to know what libraries / frameworks are being used and where to look to troubleshoot issues. Compare it to opposite approach that Ruby on Rails uses with Ruby Gems, where nothing is declared and everything is auto-loaded. From personal experience I know it becomes an absolute pain to try to workout where some_random_method is coming from and also what methods / classes I have access to.
You're right that the disadvantage is that it can become quite verbose with multiple imports and moving relative files. Modern editors and IDEs like WebStorm and Visual Studio Code have tools to automatically update the relative paths when you move a file and also automatically add the imports when you reference code in another module.
One practical solution for multiple imports is to make your own 'group' import file. Say you have a whole bunch of utility functions that you use in all your files - you can import them all into a single file and then just reference that file everywhere else:
//File: helpers/string-helpers.ts
import {toUppercase} from "./uppercase-helper";
import {truncate} from "./truncate-helper";
export const toUppercase = toUppercase;
export const truncate = truncate;
Then in any other file:
import * as StringHelpers from "../path-to/helpers/string-helpers";
...
let shoutingMessage = StringHelpers.toUppercase(message);
The disadvantage of this is that it may break tree shaking, where tools such as webpack remove unused code.
Is it possible
Not in any easy way. The ts file is a module and uses e.g. module.exports (if commonjs) that will need to be shimmed out. And that is just the runtime story. The TypeScript story will be harder and one way would be to make a .d.ts file for the module stating the contents as global.
Like I said. Not worth doing. Modules are the way forward instead of making something hacky.
It's not crazy at all. You are definitively thinking in the wrong way.
Actually what you don't like it's a common feature in all modern programming languages and it makes the code and structure of the app a lot clearer and simple to understand.
Without imports and going to old school way looks very crazy to me :)
You can have only chaos with so many global variables.

Get Angular 2 .ts files instead of .d.ts files

When I work with angular2 code I often need to see the implementation of a class, let's say the Router class.
If I click on the Router type in my IDE WebStorm, e. g. inside the constructor of another class
export class myClass {
constructor(private router: Router) {}
// ...
}
my IDE takes me to the TypeScript definition file router.d.ts inside my node_modules folder. What I want is it to take me to the original router.ts file with the implementation of the router class, not just its definition.
The original .ts file is not included in the node_modules folder structure when you get angular2 from github via the standard package.json suggested in the Angular2 Quickstart. Currently, I have to look up the original code in the official github repo.
Any ideas how to get the .ts files into my node_modules/#angular folder instead of the .d.ts files?
Sadly, it's not possible since no TS files exist. Even if you add them it still not possible since you import real angular paths which always point to the definition files. On top of that the file structure of the project does not correlate to the structure of the import string literals.
Some background and more information
The NPM package does not include .ts files, this is by design from the angular team. Up until some time ago the .ts files were indeed supplied with the NPM package.
The reasoning for removing them is to disable abuse from users accessing private classes and #internal and private APIs which is public methods/properties in the API that are not supposed to be public but must be so other angular internal classes can use them.
We used to see a lot of code samples out there doing things like import { PromiseCompleter } from 'angular2/src/facade/lang'; (before RC0) but this was changed when the project structure had a big structure refactor in RC0. This abuse was wide and it's bad, very bad... For users and for Angular PR.
The Angular project has a complex and robust build process where all of the API is moved from .ts files into d.ts files using an automated process that limits exposure. (public_api_guard)
The end result is d.ts files only.
It's also not possible to clone the git repo and use it since, again, the file structure is way way different so imports will have to change. Most importantly without the build Angular will, most likely, not work.
A solution using a different approach
However, if you debug your app you notice that you reach actual angular core .ts files in the source view of the console, this is because the NPM package comes with source map files that include the whole TS source code. Nice trick they did there.
This is what I use to dig deep into angular, it works quite great and I get a lot from it.
It's not as nice as Goto Declaration but it something...
IMO it's also easier to understand when you step through code...

How to include/NOT include a typescript file

We have a project which is an independent collection of javascript controls. We use typecript in this project and have enabled "Combine JavaScript output into file". As you can imagine this eventually compiles to a rather large JS file.
We then have a separate project where our app resides - it references some of the controls in the above project via the JS file.
My question is this: what is the best way to include only the controls we need in our project in such a way so as to contain the size of the JS file. We only want to include JS for controls we need.
Am I forced to "not combine" and include individual JS - or is there a better way to independently combine "specific" typescript files into one file.
If you have a large number of optional components, consider switching to AMD modules. This allows you to load modules on demand and was invented to solve the problem you describe.
If you currently have internal modules, you can convert them to external modules by adding an export statement. For example, this internal module:
module MyInternalModule {
export class Example {
}
}
Can be converted into an external module by adding one line of code:
module MyInternalModule {
export class Example {
}
}
export = MyInternalModule;
You can then use an import statement to load it when you need it:
import GiveItAnAlias = require('./MyInternalModule');
(You don't put .ts in that path).
You will need to supply a module flag to the compiler (or change the project settings if you are using Visual Studio):
tsc --module amd app.ts
You are now able to build a collection of modules and load them asynchronously on demand.

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