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rails--rails/actionview/app/assets/javascripts/README.md
Ross Kaffenberger 04cbaa1475 Use ES module syntax for application.js.tt and docs
This change swaps the CommonJS require() syntax in the Webpacker
application.js pack template file and in documentation examples with ES
module import syntax.

Benefits of this change include:

Provides continuity with the larger frontend community: Arguably, one of
the main draws in adopting Webpacker is its integration with Babel to
support ES module syntax. For a fresh Rails install with Webpacker, the
application.js file will be the first impression most Rails developers
have with webpack and Webpacker.  Most of the recent documentation and
examples they will find online for using other libraries will be based
on ES module syntax.

Reduces confusion: Developers commonly add ES imports to their
application.js pack, typically by following online examples, which means
mixing require() and import statements in a single file. This leads to
confusion and unnecessary friction about differences between require()
and import.

Embraces browser-friendliness: The ES module syntax forward-looking and
is meant to be supported in browsers. On the other hand, require()
syntax is synchronous by design and not browser-supported as CommonJS
originally was adopted in Node.js for server-side JavaScript. That
webpack supports require() syntax is merely a convenience.

Encourages best practices regarding optimization: webpack can statically
analyze ES modules and "tree-shake", i.e., strip out unused exports from
the final build (given certain conditions are met, including
`sideEffects: false` designation in package.json).
2020-06-16 15:12:12 -04:00

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Markdown

# Ruby on Rails unobtrusive scripting adapter
This unobtrusive scripting support file is developed for the Ruby on Rails framework, but is not strictly tied to any specific backend. You can drop this into any application to:
- force confirmation dialogs for various actions;
- make non-GET requests from hyperlinks;
- make forms or hyperlinks submit data asynchronously with Ajax;
- have submit buttons become automatically disabled on form submit to prevent double-clicking.
These features are achieved by adding certain [`data` attributes][data] to your HTML markup. In Rails, they are added by the framework's template helpers.
## Optional prerequisites
Note that the `data` attributes this library adds are a feature of HTML5. If you're not targeting HTML5, these attributes may make your HTML to fail [validation][validator]. However, this shouldn't create any issues for web browsers or other user agents.
## Installation
### npm
npm install @rails/ujs --save
### Yarn
yarn add @rails/ujs
Ensure that `.yarnclean` does not include `assets` if you use [yarn autoclean](https://yarnpkg.com/lang/en/docs/cli/autoclean/).
## Usage
### Asset pipeline
In a conventional Rails application that uses the asset pipeline, require `rails-ujs` in your `application.js` manifest:
```javascript
//= require rails-ujs
```
### ES2015+
If you're using the Webpacker gem or some other JavaScript bundler, add the following to your main JS file:
```javascript
import Rails from "@rails/ujs"
Rails.start()
```
## How to run tests
Run `bundle exec rake ujs:server` first, and then run the web tests by visiting http://localhost:4567 in your browser.
## License
rails-ujs is released under the [MIT License](MIT-LICENSE).
[data]: https://www.w3.org/TR/html5/dom.html#embedding-custom-non-visible-data-with-the-data-attributes "Embedding custom non-visible data with the data-* attributes"
[validator]: https://validator.w3.org/
[csrf]: https://api.rubyonrails.org/classes/ActionController/RequestForgeryProtection.html