From 9cfce3af4c3e6e6dbe12259c536fd69fb2a6e3ff Mon Sep 17 00:00:00 2001
From: naveentehrpariya <naveentehrpariya@gmail.com>
Date: Wed, 8 Jul 2026 17:22:39 +0530
Subject: [PATCH] fix: return the final exponent from output 'exponent'

The output === 'exponent' early return fired before the bits
auto-increment, rounding-overflow, and precision adjustments that can
bump the exponent, so it could disagree with every other output mode:
filesize(999999, {output: 'exponent'}) returned 1 while the string
output is '1 MB' and object output reports exponent 2. Feeding the
result back as a forced exponent then produced '1000 kB'. In bits
mode the disagreement covers whole ranges (125000-999999 -> 1 vs 2).

Move the early return after those adjustments so the reported
exponent always matches the exponent used to render the value.
---
 src/filesize.js             | 11 +++++++----
 tests/unit/filesize.test.js | 20 ++++++++++++++++++++
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/filesize.js b/src/filesize.js
index 1977b11..12c54f4 100644
--- a/src/filesize.js
+++ b/src/filesize.js
@@ -126,10 +126,6 @@ export function filesize(
 	e = calculatedE;
 	const autoExponent = exponent === -1 || isNaN(exponent);
 
-	if (output === EXPONENT) {
-		return e;
-	}
-
 	const { result: valueResult, e: valueExponent } = calculateOptimizedValue(
 		num,
 		e,
@@ -164,6 +160,13 @@ export function filesize(
 		e = precisionResult.e;
 	}
 
+	// Return the exponent only after every adjustment that other output
+	// modes apply (bits auto-increment, rounding overflow, precision), so
+	// it always matches the exponent reported by object output.
+	if (output === EXPONENT) {
+		return e;
+	}
+
 	u = resolveSymbol(actualStandard, bits, e, isDecimal);
 	result[1] = u;
 
diff --git a/tests/unit/filesize.test.js b/tests/unit/filesize.test.js
index 3e8ac6c..fa6a469 100644
--- a/tests/unit/filesize.test.js
+++ b/tests/unit/filesize.test.js
@@ -128,6 +128,26 @@ describe("filesize", () => {
 			assert.strictEqual(typeof result, "number");
 			assert.strictEqual(result, 1);
 		});
+
+		it("should match the object exponent when rounding overflows the unit", () => {
+			// 999999 renders as "1 MB", so the exponent is 2, not 1
+			assert.strictEqual(filesize(999999, { output: "exponent" }), 2);
+			assert.strictEqual(
+				filesize(999999, { output: "exponent" }),
+				filesize(999999, { output: "object" }).exponent,
+			);
+			// IEC: 1048575 renders as "1 MiB"
+			assert.strictEqual(filesize(1048575, { standard: "iec", output: "exponent" }), 2);
+		});
+
+		it("should match the object exponent when bits auto-increment the unit", () => {
+			// 125000 bytes = 1 Mbit, so the exponent is 2, not 1
+			assert.strictEqual(filesize(125000, { bits: true, output: "exponent" }), 2);
+			assert.strictEqual(
+				filesize(125000, { bits: true, output: "exponent" }),
+				filesize(125000, { bits: true, output: "object" }).exponent,
+			);
+		});
 	});
 
 	describe("Rounding", () => {