JSBI-calculator may somewhat match the purpose of this BigDecimal proposal.

[Leslie-Wong-H]

Came across this proposal incidentally. Quite interested and thrilled to see other developers' same need for BigDecimal in JavaScript.

Personally, I do maintain a BigDecimal-related library for arbitrary computation purposes. The principles under the hood are to wrap BigInt into a BigDecimal class and perform arithmetic computation for verbose expression. With the power of BigInt-polyfill JSBI, it is even compatible with IE11.

Hope other developers found it useful too.

JSBI-calculator

npm i jsbi-calculator