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Node.js string concatenation faster than array join in loops

By PulseAugur Editorial · [1 sources] ·

A recent performance test in Node.js 22+ indicates that the long-standing advice to use array join over string concatenation in loops is no longer accurate. When building strings within loops, direct concatenation using `+=` was found to be faster or equal to the `array.push().join()` method across various iteration counts, including up to one million iterations. This suggests that modern JavaScript engines have optimized string concatenation to avoid the quadratic performance penalties of older engines. AI

IMPACT This finding may lead developers to simplify code by using string concatenation directly in loops, potentially improving performance in certain JavaScript applications.

RANK_REASON The item discusses a performance optimization for a programming language, not a new product release or frontier research.

Read on dev.to — Claude Code tag →

AI-generated summary · Google Gemini · from 1 sources. How we write summaries →

Node.js string concatenation faster than array join in loops

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16 / 100
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The item discusses a performance optimization for a programming language, not a new product release or frontier research.
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COVERAGE [1]

  1. dev.to — Claude Code tag TIER_1 English(EN) · RAXXO Studios ·

    String Concatenation vs Array Join: I Timed the Old Advice

    <ul> <li><p>I timed string += against array push then join at four loop sizes in Node 22</p></li> <li><p>At 1 million iterations, += finished in 339ms against 437ms for push and join</p></li> <li><p>The two methods tied at 10,000 and 100,000 iterations, within a few percent eithe…

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