handle string with leading decimal separator

Author: dangowans

index.js

@@ -1,3 +1,4 @@
+const numbers = '0123456789';
 /**
  * Retrieves the computer's locale decimal separator.
  * @returns Either "." or ",".
@@ -43,7 +44,10 @@ export function parseNumeric(numericString, userParsingOptions) {
      * Remove any leading units
      */
     while (processingString !== '') {
-        if ('0123456789'.includes(processingString.charAt(0))) {
+        if (numbers.includes(processingString.charAt(0)) ||
+            (processingString.charAt(0) === '.' &&
+                processingString.length > 1 &&
+                numbers.includes(processingString.charAt(1)))) {
             break;
         }
         else {

index.ts

@@ -1,5 +1,7 @@
 type DecimalSeparator = '.' | ','
 
+const numbers = '0123456789'
+
 export interface ParsingOptions {
   decimalSeparator: DecimalSeparator
 }
@@ -16,8 +18,14 @@ export const defaultParsingOptions: ParsingOptions = {
   decimalSeparator: getLocaleDecimalSeparator()
 }
 
-export function parseNumeric(numericString: undefined | null, userParsingOptions?: Partial<ParsingOptions>): undefined
-export function parseNumeric(numericString: string, userParsingOptions?: Partial<ParsingOptions>): number
+export function parseNumeric(
+  numericString: undefined | null,
+  userParsingOptions?: Partial<ParsingOptions>
+): undefined
+export function parseNumeric(
+  numericString: string,
+  userParsingOptions?: Partial<ParsingOptions>
+): number
 
 /**
  * Converts a string into a number.
@@ -68,7 +76,12 @@ export function parseNumeric(
    */
 
   while (processingString !== '') {
-    if ('0123456789'.includes(processingString.charAt(0))) {
+    if (
+      numbers.includes(processingString.charAt(0)) ||
+      (processingString.charAt(0) === '.' &&
+        processingString.length > 1 &&
+        numbers.includes(processingString.charAt(1)))
+    ) {
       break
     } else {
       if (processingString.startsWith('-')) {
@@ -82,5 +95,4 @@ export function parseNumeric(
   return Number.parseFloat(processingString) * finalMultiplier
 }
 
-
-export default parseNumeric
+export default parseNumeric

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@cityssm/string-to-numeric",
-  "version": "0.1.2",
+  "version": "0.2.0",
   "type": "module",
   "description": "Parses formatted numeric strings into numbers. Handles cases parseFloat() misses.",
   "exports": "./index.js",

package.json

@@ -12,6 +12,10 @@ await describe('string-to-numeric', async () => {
             decimalSeparator: ','
         }), 1234.1);
     });
+    await it('Converts strings with leading decimal into numeric values', async () => {
+        assert.strictEqual(stringToNumeric('.2'), 0.2);
+        assert.strictEqual(stringToNumeric(',3', { decimalSeparator: ',' }), 0.3);
+    });
     await it('Converts strings with leading units into numeric values', async () => {
         assert.strictEqual(stringToNumeric('$2'), 2);
         assert.strictEqual(stringToNumeric('# 456'), 456);

test/test.js

@@ -20,6 +20,12 @@ await describe('string-to-numeric', async () => {
     )
   })
 
+  await it('Converts strings with leading decimal into numeric values', async () => {
+    assert.strictEqual(stringToNumeric('.2'), 0.2)
+
+    assert.strictEqual(stringToNumeric(',3', {decimalSeparator: ','}), 0.3)
+  })
+
   await it('Converts strings with leading units into numeric values', async () => {
     assert.strictEqual(stringToNumeric('$2'), 2)