46. How Arrays are Implemented in JavaScript (V8)? – PART 4- Be careful: Misuses of Array

Опубликовано: 21 Февраль 2026
на канале: Miss Xing (邢老师)

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#MissXing #JavaScript #javascriptdatatype
Misuse of Arrays:
Avoid holes
Avoid element kind transitions
Avoid polymorphism
Avoid reading beyond the length of the array
JavaScript engine has to perform expensive prototype chain lookups. Once a load has run into this situation, V8 remembers that “this load needs to deal with special cases”, and it will never be as fast again as it was before reading out-of-bounds.
Fill the array in the reverse order like arr[1000], arr[999]and so on
Add a non-numeric property like arr.name=‘Miss Xing’
Prefer arrays over array-like objects

Source code:
https://github.com/TinaXing2012/javas...