Knockout-ESNext

A complete overhaul of the Knockout.js library and build process.

Making Knockout.js slicker, faster, more maintainable than ever.

Version scheme is v3.5.1xxx, where 3.5.1 is the initial Knockout version this library was forked off, and xxx the modifications since then.

Changes (in code):

• Rewrote all library code in ES6+ supported in all modern browsers
• Use native means for iterations, mappings etc. instead of former helper functions (like ko.utils.arrayForEach)
• Reduced indirections by inlining function bodies via Rollup inline-macros plugin
• Turned former source fragments into ES modules
  • Retained most of the original names & structure, so catchup & diffing with original Knockout.js remains possible
  • Easy circular-dependency detection through ESM imports/exports
  • No more worries about loading order of fragments, no more file concatenation at all
• Internals are now self-contained & namespace-agnostic
  • no more ko.foo.bar references or assignments internally
  • ko.js being the only source of truth about what is exposed publicly (including legacy aliases)
  • override-points like ko.onError are setters in ko.js, so we gain full control over what can be overridden
• Removed historic browser support (IE, earliest Firefox etc)
• Removed jQuery support
• Kept all ~1300 tests working with very few changes:
  • Added tests for type checking (ko.isObservable etc) in basicTypeCheckBehaviors.js
  • Removed IE/jQuery-related tests

Changes (in behavior)

• When using extend({notify: 'always'}) with observables/computeds, their current default OR custom equalityComparer is now memorized and can be restored by using the extender again with anything other than 'always'. Original Knockout would only reassign its default equality comparer (valuesArePrimitiveAndEqual).

Changes (build process):

• Removed Google Closure Compiler and all code soothing its side-effects (ko.exportSymbol)
• Using Rollup + Terser plugin for build & minification
• Wrote Rollup plugin rollup-plugin-inline-macros.js, allowing to "inline" frequently used helper functions & avoid function calls in hot code paths
• Now exporting the Knockout.js library in 3 flavors:
  • Minified UMD (knockout.js)
  • Minified ES Module (knockout.esm.js)
  • Non-minified UMD debug version incl. sourcemap (knockout.debug.js & knockout.debug.js.map, not part of the knockout-esnext NPM package)
• Removed deprecated PhantomJS
• Removed Grunt
• Added ESLint for code quality checks

Changes (testing/debugging)

• After changing any source file during browser testing (spec/runner.html), you now have to run the build task before the next test-run:

  • npm run build

  This will rebuild the build/knockout.debug.js used by runner.html.
• The debug version now has a sourcemap generated alongside it (knockout.debug.js.map), so you can attach your IDE's debugger to e.g. runner.html and add breakpoints inside the actual source files rather than the generated knockout.debug.js.

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Knockout

Knockout is a JavaScript MVVM (a modern variant of MVC) library that makes it easier to create rich, desktop-like user interfaces with JavaScript and HTML. It uses observers to make your UI automatically stay in sync with an underlying data model, along with a powerful and extensible set of declarative bindings to enable productive development.

Getting started

Totally new to Knockout? The most fun place to start is the online interactive tutorials.

For more details, see

• Documentation on the project's website
• Online examples at http://knockoutjs.com/examples/

Downloading Knockout-ESNext

You can download released versions of Knockout-ESNext from Github, or the original Knockout from the project's website.

For Node.js developers, Knockout-ESNext is also available from npm - just run npm install knockout-esnext.

Building Knockout-ESNext from sources

If you prefer to build the library yourself:

1. Clone the repo from GitHub

   git clone https://github.com/justlep/knockout-esnext.git
   cd knockout-esnext

2. Acquire build dependencies.

   Make sure you have Node.js installed on your workstation. This is only needed to build Knockout from sources. Knockout itself has no dependency on Node.js once it is built (it works with any server technology or none). Now run:

   npm install

3. Start the build

   npm run build

   Now you'll find the built files in build/.

Running the tests

If you want to run the specs in Node.js

npm test

Or, if you want to run the specs in a browser (e.g., for debugging), simply open spec/runner.html in your browser.

License

MIT license - http://www.opensource.org/licenses/mit-license.php