Add code comments to the AmountInput HOC

src/views/shared/amount-input/amount-input.jsx

@@ -43,6 +43,12 @@ function AmountInput (Component) {
       }
     }, [amount, showInFiat, isAmountMoreThanFunds, isAmountCompressedInvalid])
 
+    /**
+     * Converts an amount in tokens to fiat. It takes into account the prefered currency
+     * of the user.
+     * @param {BigNumber} tokensAmount - Amount to be converted to fiat
+     * @returns fiatAmount
+     */
     function convertAmountToFiat (tokensAmount) {
       const fixedTokenAmount = getFixedTokenAmount(tokensAmount.toString(), account.token.decimals)
 
@@ -54,12 +60,24 @@ function AmountInput (Component) {
       ).toFixed(2)
     }
 
+    /**
+     * Converts an amount in fiat to tokens.
+     * @param {Number} fiatAmount - Amount to be converted to tokens
+     * @returns
+     */
     function convertAmountToTokens (fiatAmount) {
       const tokensAmount = fiatAmount / account.token.USD
 
-      return parseUnits(tokensAmount.toFixed(account.token.decimals))
+      return parseUnits(tokensAmount.toFixed(account.token.decimals), account.token.decimals)
     }
 
+    /**
+     * Validates the new amount introduced by the user. It checks:
+     * 1. The amount is not negative.
+     * 2. The amount + fees doesn't exceed the account balance.
+     * 3. The amount is supported by Hermez.
+     * @param {BigNumber} newAmount - New amount to be checked.
+     */
     function checkAmountValidity (newAmount) {
       const fee = getTransactionFee(transactionType, newAmount, account.token, l2Fee, gasPrice)
       const newAmountWithFee = newAmount.add(fee)
@@ -72,6 +90,12 @@ function AmountInput (Component) {
       }
     }
 
+    /**
+     * Handles input change events. It's going to check that the input value is a valid
+     * amount and calculate both the tokens and fiat amounts for a value. It will also
+     * trigger the validation checks.
+     * @param {InputEvent} event - Input event
+     */
     function handleInputChange (event) {
       if (INPUT_REGEX.test(event.target.value)) {
         if (showInFiat) {
@@ -96,6 +120,11 @@ function AmountInput (Component) {
       }
     }
 
+    /**
+     * Handles the "Max" button click. It will calculate the max possible amount that a
+     * user can send in a transaction based on the account balance. It also takes the fee
+     * into account (if applicable).
+     */
     function handleSendAll () {
       const maxPossibleAmount = BigNumber.from(account.balance)
       const maxAmountWithoutFee = getMaxTxAmount(transactionType, maxPossibleAmount, account.token, l2Fee, gasPrice)
@@ -113,6 +142,11 @@ function AmountInput (Component) {
       checkAmountValidity(maxAmountWithoutFee)
     }
 
+    /**
+     * Handles the change between tokens and fiat. It will update the value of the input
+     * with the appropiate value (fiat if the previous value was tokens or tokens if the
+     * previous value was fiat).
+     */
     function handleSwapCurrency () {
       const newValue = showInFiat
         ? getFixedTokenAmount(amount.tokens, account.token.decimals)