Array fill method vs for loop performance validation

When adding an element to an array, measure the performance of push, spread syntax and concat. The case is when original array must contain the new element, thus modifying it in process.

flatMap vs flat map

dev null

JSON.stringify vs slice

What's faster to locate a character's index within a string, findIndex or recursion?

- https://github.com/iriscouch/bigdecimal.js/tree/v0.6.1 - https://github.com/MikeMcl/bignumber.js/tree/v9.0.0 - https://github.com/MikeMcl/big.js/tree/v5.2.2 - https://github.com/MikeMcl/decimal.js/tree/v10.2.0 - https://github.com/infusion/Fraction.js/tree/v4.0.12