fix: fromWei() parsing of large numbers > 10^20 (#6882)

* Fix scientific notation parsing for large numbers with BigInt

Prevent automatic conversion to scientific notation for numbers >= 10^21 by using BigInt, ensuring accurate string representations and avoiding parsing errors in fromWei function.

* Update Tests for scientific notation number parsing.

* refactor: minor code cleaning

* docs: Update changelog for #6882

* Update CHANGELOG.md

---------

Co-authored-by: Alex <alex.luu@mail.utoronto.ca>
Co-authored-by: Alex <luu.alex98@gmail.com>

packages/web3-utils/CHANGELOG.md

@@ -199,4 +199,9 @@ Documentation:
 
 - replaced our eventEmitter to EventEmitter3 to support react native builds (#6253)
 
-## [Unreleased]
+## [Unreleased]
+
+### Fixed
+
+- fixed erroneous parsing of big numbers in the `fromWei(...)` function (#6880)
+

packages/web3-utils/src/converters.ts

@@ -411,6 +411,13 @@ export const toHex = (
  */
 export const toNumber = (value: Numbers): number | bigint => {
  if (typeof value === 'number') {
+ if (value > 1e+20) {
+ // JavaScript converts numbers >= 10^21 to scientific notation when coerced to strings,
+ // leading to potential parsing errors and incorrect representations.
+ // For instance, String(10000000000000000000000) yields '1e+22'.
+ // Using BigInt prevents this
+ return BigInt(value);
+ }
  return value;
  }
 

packages/web3-utils/test/fixtures/converters.ts

@@ -279,7 +279,10 @@ const conversionBaseData: [[Numbers, EtherUnits], string][] = [
 
 export const fromWeiValidData: [[Numbers, EtherUnits], string][] = [
  ...conversionBaseData,
- [['0xff', 'wei'], '255'],
+ [['0xff', 'wei'], '255'],
+ [[1e+22, 'ether'], '10000'],
+ [[19999999999999991611392, 'ether'], '19999.999999999991611392'],
+ [[1.9999999999999991611392e+22, 'ether'], '19999.999999999991611392'],
 ];
 
 export const toWeiValidData: [[Numbers, EtherUnits], string][] = [