Simplify conditional expressions in reading utilities

src/read/digits.ts

@@ -18,6 +18,5 @@ const DIGIT_MAP: readonly string[] = [
  * Get Vietnamese word for a digit
  */
 export function getDigitWord(digit: string): string {
-  const d = Number(digit)
-  return DIGIT_MAP[d] || ''
+  return DIGIT_MAP[Number(digit)] || ''
 }

src/read/groups.ts

@@ -11,11 +11,13 @@ import { allFollowingGroupsAreZero } from './utils.ts'
  */
 export function calculateGroupTypes(groupCount: number): number[] {
   const groupTypes: number[] = []
+
   for (let i = groupCount - 1, type = 0; i >= 0; i--) {
     groupTypes[i] = type
     type++
     if (type === 4) type = 1 // cycle back after billion
   }
+
   return groupTypes
 }
 
@@ -101,21 +103,13 @@ export function processGroup(
   const positionFromRight = groups.length - 1 - index
   const hasTrailingZeros = allFollowingGroupsAreZero(groups, index)
 
-  if (index === 0) {
-    const nextGroupType = groups.length > 1 ? groupTypes[1] : -1
-    return processFirstGroup(
-      group,
-      type,
-      nextGroupType,
-      positionFromRight,
-      hasTrailingZeros,
-    )
-  }
-
-  return processSubsequentGroup(
-    group,
-    type,
-    positionFromRight,
-    hasTrailingZeros,
-  )
+  return index === 0
+    ? processFirstGroup(
+        group,
+        type,
+        groups.length > 1 ? groupTypes[1] : -1, // nextGroupType: the type of the next group to determine if we're before billion group
+        positionFromRight,
+        hasTrailingZeros,
+      )
+    : processSubsequentGroup(group, type, positionFromRight, hasTrailingZeros)
 }

src/read/three-digits.ts

@@ -4,19 +4,20 @@ import { getDigitWord } from './digits.ts'
  * Read the "hundreds" digit
  */
 function readHundreds(first: string, hasHundredsPosition: boolean): string {
-  if (!hasHundredsPosition) return ''
-  return `${getDigitWord(first)} trăm`
+  return !hasHundredsPosition ? '' : `${getDigitWord(first)} trăm`
 }
 
 /**
  * Read the "tens" digit
  */
 function readTens(second: string, hasTensPosition: boolean): string {
-  if (!hasTensPosition) return ''
-
-  if (second === '0') return ' lẻ'
-  if (second === '1') return ' mười'
-  return ` ${getDigitWord(second)} mươi`
+  return !hasTensPosition
+    ? ''
+    : second === '0'
+      ? ' lẻ'
+      : second === '1'
+        ? ' mười'
+        : ` ${getDigitWord(second)} mươi`
 }
 
 /**
@@ -41,6 +42,7 @@ function readOnes(
   if (last !== '0') {
     return ` ${getDigitWord(last)}`
   }
+
   return ''
 }
 
@@ -94,20 +96,12 @@ export function readFirstGroupBeforeBillion(group: string): string {
  * Read the first group in the number sequence (normal case)
  */
 export function readFirstGroup(group: string): string {
-  if (isAllZeros(group)) {
-    return 'không'
-  }
-
-  return readThreeDigitsCore(group)
+  return isAllZeros(group) ? 'không' : readThreeDigitsCore(group)
 }
 
 /**
  * Read the later (non-first) group in the number sequence
  */
 export function readSubsequentGroup(group: string): string {
-  if (isAllZeros(group)) {
-    return ''
-  }
-
-  return readThreeDigitsCore(group)
+  return isAllZeros(group) ? '' : readThreeDigitsCore(group)
 }

src/read/utils.ts

@@ -23,9 +23,11 @@ export function allFollowingGroupsAreZero(
 ): boolean {
   for (let j = index + 1; j < groups.length; j++) {
     const g = groups[j]
+
     if (g !== '000' && g !== '00' && g !== '0') {
       return false
     }
   }
+
   return true
 }