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JavaScript’s a mess – and that’s a good thing

原文链接: 2ality.com

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JavaScript’s a mess – and that’s a good thing

[2018-02-05] dev, javascript, esnext

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JavaScript never removes old features – new versions are always backward compatible. I wish we could clean it up, but staying compatible has too many benefits, as I’ll explain in this blog post.

The benefits of backward compatibility #

These are benefits of staying backward compatible:

  • It is trivially easy to migrate to new language versions. For example, all old code was already compatible with ES6 when it came out.
    • Only ES modules are relatively difficult to adopt – but they kind of do break backward compatibility.
  • It avoids versioned code. If you allow some code to be “old” and some code to be “new”:
    • Language engines and tools become more complicated.
    • Programmers need to be aware of versions.
    • You can’t move code around, anymore (if a code base is mixed).

Tips for dealing with JavaScript’s expanding feature set #

  • Teaching and learning: you can mostly ignore old features, apart from what they look like and – roughly – what they do.
  • Let linters help you with using the language properly.
  • Let Prettier help you with formatting source code properly.

A cleaner JavaScript #

If you want to program in as clean a JavaScript as possible, there is much you can ignore (some suggestions are more radical than others):

  • var. Use let and const, instead.
  • function. Use only arrows and method definitions. Benefit: handling this becomes much simpler (details).
  • Promises. Use only async functions. Learn what to watch out for (you can’t ignore Promises as completely as var).
  • Iterating over objects. Use Maps, instead.
  • Loops: for-in (avoid always), for (avoid if you can). Use for-of, instead.
  • arguments. Use rest parameters (...args), instead.
  • Function.prototype.apply(). Use the spread operator (f(...myArray)), instead.
  • Constructor functions. Use classes, instead.
  • IIFEs. Use blocks, instead.

Wish #

  • typeof vs. instanceof is too complicated. This blog post describes a library for simplifying things.

Further reading #

Dr. Axel Rauschmayer


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via: http://2ality.com/2018/02/js-backward-compatibility.html

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