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JavaScript delete operator might cause some unexpected performance issues.
- Using the delete operator in JavaScript can lead to unexpected performance issues, as observed during benchmarking in v8 engine and Safari v18.5.
- Deleting object keys with delete operator impacted code performance almost 3 times worse compared to manually setting the key to undefined or false.
- The performance issue with the delete operator was reproducible in Safari v18.5 and Chromium-based browsers, indicating a broader impact beyond the v8 engine.
- A benchmarking code example showcased the performance impact of delete vs. manually setting keys to false, highlighting the significant difference in execution times.
- Testing conducted in various environments like Chrome, Safari, and Node consistently showed the delete method's execution time being notably slower than manually setting keys to false.
- In Node v24.2.0, Chrome Version 136.0.7103.114, and Safari 18.5, the performance issue with the delete operator persisted.
- The underlying reason for the performance impact of delete in JavaScript engines like v8 and Nitro (used in Safari) is not officially confirmed but may relate to optimizations geared for hash map operations being lost.
- Optimizations for hash map operations could be compromised when using delete in JavaScript objects, affecting performance in scenarios with frequent read operations.
- Consider avoiding heavy use of delete for objects used as lookups with frequent read operations to maintain optimal runtime and performance.
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