Reduce With a Summary Accumulator

HardHigher Order FunctionsReducePRO

Compute completed-attempt averages with JavaScript reduce while ignoring incomplete records. This hard exercise asks learners to use a summary accumulator with both total and count, then choose a null fallback when no attempts qualify.

What you'll practice

Compute completed-attempt averages with JavaScript reduce while ignoring incomplete records
Asks learners to use a summary accumulator with both total and count
Then choose a null fallback when no attempts qualify

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