[audreyt]

Thanks! The aim for the chapter is indeed to show how ES6 and AngularJS simplify a typical web application like this.

The version at https://github.com/audreyt/500lines/tree/master/spreadsheet/... has exactly the same line count, but with more idiomatic workarounds that's less clear to students new to web development (the audience of this book).

It is possible to replace AngularJS (the only external library) with regular blur/focus/change handler as @xem shows — without affecting the line counts — but the separation of concerns between view, logic and worker would be less clear.

[audreyt]

Comparing the ES5-DOM-only version: https://github.com/audreyt/500lines/tree/master/spreadsheet/... with with the AngularJS-with-ES5 version: https://github.com/audreyt/500lines/tree/master/spreadsheet/... would illustrate the issue of separation of concerns.

The DOM-only version had to construct its own view in JS, and use an additional #_A1 encoding to fill in calculated values into display, while the AngularJS version is declarative in that regard.