Reduce array to value

Reduce array to value in JavaScript — with two ready prompts: the immediate one, and the one that makes it stick.

2prompt heights
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2 ready prompts

Written for the moment this actually comes up.

Improve — make it easier to accept

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Before I hand this to QA, make the reduction easy to verify: place the total at the top of the…
Before I hand this to QA, make the reduction easy to verify: place the total at the top of the function, use a clear variable name totalSum, handle empty arrays by returning 0, and add one short in-line comment showing the initial value. Keep the code compact so reviewers can spot arithmetic errors quickly.

Become — change the pattern

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Every quarter I patch reducers because unexpected values like null, strings, or empty arrays cause…

I keep shipping reducers that break on edge data

Every quarter I patch reducers because unexpected values like null, strings, or empty arrays cause exceptions or NaN on the dashboard. I want one change that stops most of these incidents without bloating code in every module. What habit or small wrapper should I adopt to prevent these bugs going forward?

Next to this one

Other programming language work people do in JavaScript.

Every task here came from the work, not from a feature list — which is why the prompts name what you want done and never the button that does it. The tool changes; the work does not.
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The rest of the map

Same library, five ways in.