Use decimal js

package.json

@@ -51,6 +51,7 @@
   "dependencies": {
     "@types/pbkdf2": "^3.1.2",
     "big-varint": "^0.1.3",
+    "decimal.js": "^10.4.3",
     "pbkdf2": "^3.1.2"
   }
 }

packages/massa-web3/src/experimental/basicElements/mas.ts

@@ -1,4 +1,5 @@
-import { FIRST, FIVE, ONE, ZERO } from '../utils'
+import Decimal from 'decimal.js'
+import { FIRST, ONE } from '../utils'
 import { U64, fromNumber } from './serializers/number/u64'
 
 export const NB_DECIMALS = 9
@@ -104,7 +105,7 @@ export function fromString(value: string): Mas {
  * Converts a Mas value to a string with rounding approximation.
  *
  * @param value - The Mas value.
- * @param decimalPlaces - The number of decimal places to include in the string. If null, trailing zeros are removed.
+ * @param decimalPlaces - The number of decimal places to include in the string.
  * @returns The value as a string.
  *
  * @throws An error if the value is too large to be represented by a U256.
@@ -113,33 +114,15 @@ export function toString(
   value: Mas,
   decimalPlaces: number | null = null
 ): string {
-  if (value >= BigInt(ONE) << BigInt(SIZE_U256_BIT)) {
+  if (BigInt(value) >= BigInt(ONE) << BigInt(SIZE_U256_BIT)) {
     throw new Error(ERROR_VALUE_TOO_LARGE)
   }
 
-  const valueString = value.toString()
-  const integerPart = valueString.slice(ZERO, -NB_DECIMALS) || '0'
-  let decimalPart = valueString.slice(-NB_DECIMALS).padStart(NB_DECIMALS, '0')
+  const scaledValue = new Decimal(value.toString()).div(`1e+${NB_DECIMALS}`)
 
-  if (decimalPlaces === null) {
-    // If decimalPlaces is null, remove trailing zeros from the decimal part
-    decimalPart = decimalPart.replace(/0+$/, '')
-  } else if (decimalPlaces < NB_DECIMALS) {
-    // If decimalPlaces is specified and less than NB_DECIMALS, handle rounding
-    const roundingDigit = parseInt(decimalPart[decimalPlaces])
-
-    if (roundingDigit >= FIVE) {
-      // If the rounding digit is 5 or greater, round up
-      decimalPart = (
-        BigInt(decimalPart.slice(ZERO, decimalPlaces)) + BigInt(ONE)
-      )
-        .toString()
-        .padStart(decimalPlaces, '0')
-    } else {
-      // Otherwise, truncate the decimal part to the specified number of places
-      decimalPart = decimalPart.slice(ZERO, decimalPlaces)
-    }
+  if (decimalPlaces !== null) {
+    return scaledValue.toFixed(decimalPlaces, Decimal.ROUND_HALF_UP)
   }
 
-  return decimalPart.length ? `${integerPart}.${decimalPart}` : integerPart
+  return scaledValue.toString()
 }