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by brlewis 2696 days ago
One problem with the math for the ROI calculation is that catching a bug with a test is counted the same as catching a bug while you're typing the buggy code. Type checking lets you catch bugs sooner, thus more cheaply.

Another problem is that it focuses on bugs that make it out to production. Maybe for some projects production bugs are so costly that pre-production bugs are relatively negligible, but for most projects you can't treat pre-production bugs as 0 cost.
1 comments
ericelliott 2696 days ago
Some good reasons for that:

1. I get type feedback in my browser with inference. 2. I get near real-time feedback from TDD on file save. 3. I get real-time lint feedback, too.

The net result is I get several multiples better bug coverage than TypeScript alone can provide at about the same speed -- while writing idiomatic JS.

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ng12 2696 days ago
> TypeScript alone can provide at about the same speed

If writing your unit tests contributes less overhead than writing TypeScript types you're doing something horribly wrong.

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ericelliott 2695 days ago
It's not less overhead, but you can't skip TDD with TypeScript because at least 80% of bugs are not detectable by TypeScript.
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