fix: support scientific notation in parse() for roundtrip consistency

src/index.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from '@jest/globals';
-import { ms } from './index';
+import { ms, type StringValue } from './index';
 
 describe('ms(string)', () => {
   it('should not throw an error', () => {
@@ -329,6 +329,29 @@ describe('ms(number)', () => {
   });
 });
 
+// roundtrip
+
+describe('ms(roundtrip)', () => {
+  it('should roundtrip for common values', () => {
+    expect(ms(ms('1s'))).toBe('1s');
+    expect(ms(ms('1m'))).toBe('1m');
+    expect(ms(ms('1h'))).toBe('1h');
+    expect(ms(ms('1d'))).toBe('1d');
+    expect(ms(ms('1w'))).toBe('1w');
+    expect(ms(ms('1y'))).toBe('1y');
+  });
+
+  it('should not return NaN for format() output with large numbers', () => {
+    const formatted = ms(Number.MAX_SAFE_INTEGER) as StringValue;
+    expect(Number.isNaN(ms(formatted))).toBe(false);
+  });
+
+  it('should not return NaN for format() output with large negative numbers', () => {
+    const formatted = ms(-Number.MAX_SAFE_INTEGER) as StringValue;
+    expect(Number.isNaN(ms(formatted))).toBe(false);
+  });
+});
+
 // invalid inputs
 
 describe('ms(invalid inputs)', () => {

src/index.ts

@@ -75,7 +75,7 @@ export function parse(str: string): number {
     );
   }
   const match =
-    /^(?<value>-?\d*\.?\d+) *(?<unit>milliseconds?|msecs?|ms|seconds?|secs?|s|minutes?|mins?|m|hours?|hrs?|h|days?|d|weeks?|w|months?|mo|years?|yrs?|y)?$/i.exec(
+    /^(?<value>-?\d*\.?\d+(?:e[+-]?\d+)?) *(?<unit>milliseconds?|msecs?|ms|seconds?|secs?|s|minutes?|mins?|m|hours?|hrs?|h|days?|d|weeks?|w|months?|mo|years?|yrs?|y)?$/i.exec(
       str,
     );
 

src/parse.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from '@jest/globals';
-import { parse } from './index';
+import { format, parse } from './index';
 
 describe('parse(string)', () => {
   it('should not throw an error', () => {
@@ -142,6 +142,27 @@ describe('parse(long string)', () => {
   });
 });
 
+// scientific notation
+
+describe('parse(scientific notation)', () => {
+  it('should handle scientific notation in number part', () => {
+    expect(parse('1e3ms')).toBe(1000);
+    expect(parse('1.5e2ms')).toBe(150);
+    expect(parse('1e+3ms')).toBe(1000);
+    expect(parse('1e-3ms')).toBe(0.001);
+  });
+
+  it('should handle format() output for very large values', () => {
+    const formatted = format(Number.MAX_SAFE_INTEGER);
+    expect(Number.isNaN(parse(formatted))).toBe(false);
+  });
+
+  it('should handle format() output for very small negative values', () => {
+    const formatted = format(-Number.MAX_SAFE_INTEGER);
+    expect(Number.isNaN(parse(formatted))).toBe(false);
+  });
+});
+
 // invalid inputs
 
 describe('parse(invalid inputs)', () => {