Round large exponential numbers

3 files changed, 23 insertions, 6 deletions

diff --git a/ui/app/components/pages/confirm-token-transaction-base/confirm-token-transaction-base.component.js b/ui/app/components/pages/confirm-token-transaction-base/confirm-token-transaction-base.component.js
index 365ae216e..acaed383a 100644
--- a/ui/app/components/pages/confirm-token-transaction-base/confirm-token-transaction-base.component.js
+++ b/ui/app/components/pages/confirm-token-transaction-base/confirm-token-transaction-base.component.js
@@ -5,6 +5,7 @@ import {
   formatCurrency,
   convertTokenToFiat,
   addFiat,
+  roundExponential,
 } from '../../../helpers/confirm-transaction/util'
 
 export default class ConfirmTokenTransactionBase extends Component {
@@ -42,7 +43,8 @@ export default class ConfirmTokenTransactionBase extends Component {
       return this.context.t('noConversionRateAvailable')
     } else {
       const fiatTransactionAmount = this.getFiatTransactionAmount()
-      return formatCurrency(fiatTransactionAmount, currentCurrency)
+      const roundedFiatTransactionAmount = roundExponential(fiatTransactionAmount)
+      return formatCurrency(roundedFiatTransactionAmount, currentCurrency)
     }
   }
 
@@ -54,7 +56,8 @@ export default class ConfirmTokenTransactionBase extends Component {
     } else {
       const fiatTransactionAmount = this.getFiatTransactionAmount()
       const fiatTotal = addFiat(fiatTransactionAmount, fiatTransactionTotal)
-      return formatCurrency(fiatTotal, currentCurrency)
+      const roundedFiatTotal = roundExponential(fiatTotal)
+      return formatCurrency(roundedFiatTotal, currentCurrency)
     }
   }
 
diff --git a/ui/app/helpers/confirm-transaction/util.js b/ui/app/helpers/confirm-transaction/util.js
index f015b2bf5..a37778c19 100644
--- a/ui/app/helpers/confirm-transaction/util.js
+++ b/ui/app/helpers/confirm-transaction/util.js
@@ -3,6 +3,7 @@ import currencies from 'currency-formatter/currencies'
 import abi from 'human-standard-token-abi'
 import abiDecoder from 'abi-decoder'
 import ethUtil from 'ethereumjs-util'
+import BigNumber from 'bignumber.js'
 
 abiDecoder.addABI(abi)
 
@@ -137,3 +138,11 @@ export function convertTokenToFiat ({
 export function hasUnconfirmedTransactions (state) {
   return unconfirmedTransactionsCountSelector(state) > 0
 }
+
+export function roundExponential (value) {
+  const PRECISION = 4
+  const bigNumberValue = new BigNumber(value)
+
+  // In JS, numbers with exponentials greater than 20 get displayed as an exponential.
+  return bigNumberValue.e > 20 ? Number(bigNumberValue.toPrecision(PRECISION)) : value
+}
diff --git a/ui/app/selectors/confirm-transaction.js b/ui/app/selectors/confirm-transaction.js
index 8f8e0ea74..9548cf75e 100644
--- a/ui/app/selectors/confirm-transaction.js
+++ b/ui/app/selectors/confirm-transaction.js
@@ -1,6 +1,7 @@
 import { createSelector } from 'reselect'
 import txHelper from '../../lib/tx-helper'
 import { calcTokenAmount } from '../token-util'
+import { roundExponential } from '../helpers/confirm-transaction/util'
 
 const unapprovedTxsSelector = state => state.metamask.unapprovedTxs
 const unapprovedMsgsSelector = state => state.metamask.unapprovedMsgs
@@ -133,7 +134,8 @@ export const tokenAmountAndToAddressSelector = createSelector(
       const toParam = params.find(param => param.name === TOKEN_PARAM_TO)
       const valueParam = params.find(param => param.name === TOKEN_PARAM_VALUE)
       toAddress = toParam ? toParam.value : params[0].value
-      tokenAmount = valueParam ? Number(valueParam.value) : Number(params[1].value)
+      const value = valueParam ? Number(valueParam.value) : Number(params[1].value)
+      tokenAmount = roundExponential(value)
     }
 
     return {
@@ -151,7 +153,8 @@ export const approveTokenAmountAndToAddressSelector = createSelector(
 
     if (params && params.length) {
       toAddress = params.find(param => param.name === TOKEN_PARAM_SPENDER).value
-      tokenAmount = Number(params.find(param => param.name === TOKEN_PARAM_VALUE).value)
+      const value = Number(params.find(param => param.name === TOKEN_PARAM_VALUE).value)
+      tokenAmount = roundExponential(value)
     }
 
     return {
@@ -170,11 +173,13 @@ export const sendTokenTokenAmountAndToAddressSelector = createSelector(
 
     if (params && params.length) {
       toAddress = params.find(param => param.name === TOKEN_PARAM_TO).value
-      tokenAmount = Number(params.find(param => param.name === TOKEN_PARAM_VALUE).value)
+      let value = Number(params.find(param => param.name === TOKEN_PARAM_VALUE).value)
 
       if (tokenDecimals) {
-        tokenAmount = calcTokenAmount(tokenAmount, tokenDecimals)
+        value = calcTokenAmount(value, tokenDecimals)
       }
+
+      tokenAmount = roundExponential(value)
     }
 
     return {