Merge pull request #16 from HyperPlay-Gaming/feat/add_get_decimal_fro…

…m_amount

[Feat] add getDecimalNumberFromAmount and tests

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@hyperplay/utils",
-  "version": "0.0.14",
+  "version": "0.0.15",
   "description": "",
   "main": "index.js",
   "scripts": {

src/getAmount.test.ts

@@ -1,4 +1,4 @@
-import { getAmount } from './getAmount'
+import { getAmount, getDecimalNumberFromAmount } from './getAmount'
 
 describe('getAmount util', () => {
   test('get amount of 10 with 18 decimals', () => {
@@ -34,3 +34,18 @@ describe('getAmount util', () => {
     expect(amt).toBe('0')
   })
 })
+
+describe('getDecimalNumberFromAmount util', () => {
+  test('get amount of 0 with 18 decimals', () => {
+    const amt = getDecimalNumberFromAmount('0', 18).toString()
+    expect(amt).toBe('0')
+  })
+
+  test('get amount of 1000 with 18 decimals', () => {
+    const amt = getDecimalNumberFromAmount(
+      '1000000000000010101010',
+      18
+    ).toString()
+    expect(amt).toBe('1000.00000000001010101')
+  })
+})

src/getAmount.ts

@@ -1,5 +1,7 @@
 import BigNumber from 'bignumber.js'
 
+// bigint does not support decimals/fractional numbers so we use BigNumber.js
+
 export function getAmount(amount: number, decimals: number) {
   // ethers cannot interpret scientific notation strings so return the full string
   BigNumber.config({ EXPONENTIAL_AT: 78 })
@@ -10,3 +12,13 @@ export function getAmount(amount: number, decimals: number) {
   const amountInDecimals = amt.multipliedBy(pow)
   return amountInDecimals
 }
+
+export function getDecimalNumberFromAmount(amount: string, decimals: number) {
+  // ethers cannot interpret scientific notation strings so return the full string
+  BigNumber.config({ EXPONENTIAL_AT: 78 })
+  const value = new BigNumber(amount)
+  const exponent = BigNumber(decimals)
+  const ten = new BigNumber(10)
+  const denominator = ten.pow(exponent)
+  return value.div(denominator)
+}