From 08f67c4e87d7a2ad32fc3e4038f57e2699ef0e8d Mon Sep 17 00:00:00 2001
From: Masashi Hirano <cherrydog07@gmail.com>
Date: Fri, 3 Aug 2018 00:52:27 +0900
Subject: [PATCH] util: support BigInt in util.format

Adding support for BigInt in util.format and console.log.
Placeholder `%d` is replaced as Number when BigInt is set in
second argument.
Now, `util.format('%d', 1180591620717411303424n)` returns
`'1.1805916207174113e+21'`.
However, expected result is `'1180591620717411303424'`.
---
 doc/api/util.md                   | 2 +-
 lib/util.js                       | 8 +++++++-
 test/parallel/test-util-format.js | 8 ++++++++
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/doc/api/util.md b/doc/api/util.md
index d29fbfc5b7f050..96838fb8e2f77c 100644
--- a/doc/api/util.md
+++ b/doc/api/util.md
@@ -198,7 +198,7 @@ Each placeholder token is replaced with the converted value from the
 corresponding argument. Supported placeholders are:
 
 * `%s` - `String`.
-* `%d` - `Number` (integer or floating point value).
+* `%d` - `Number` (integer or floating point value) or `BigInt`.
 * `%i` - Integer.
 * `%f` - Floating point value.
 * `%j` - JSON. Replaced with the string `'[Circular]'` if the argument
diff --git a/lib/util.js b/lib/util.js
index 89c86cb7fd0050..24b7a931396aac 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -291,7 +291,13 @@ function formatWithOptions(inspectOptions, f) {
             tempStr = tryStringify(arguments[a++]);
             break;
           case 100: // 'd'
-            tempStr = `${Number(arguments[a++])}`;
+            const tempNum = arguments[a++];
+            // eslint-disable-next-line valid-typeof
+            if (typeof tempNum === 'bigint') {
+              tempStr = `${tempNum}n`;
+            } else {
+              tempStr = `${Number(tempNum)}`;
+            }
             break;
           case 79: // 'O'
             tempStr = inspect(arguments[a++], inspectOptions);
diff --git a/test/parallel/test-util-format.js b/test/parallel/test-util-format.js
index a8adf936719932..5a85870f1a33c0 100644
--- a/test/parallel/test-util-format.js
+++ b/test/parallel/test-util-format.js
@@ -68,6 +68,14 @@ assert.strictEqual(util.format('%d', -0.5), '-0.5');
 assert.strictEqual(util.format('%d', ''), '0');
 assert.strictEqual(util.format('%d %d', 42, 43), '42 43');
 assert.strictEqual(util.format('%d %d', 42), '42 %d');
+assert.strictEqual(
+  util.format('%d', 1180591620717411303424),
+  '1.1805916207174113e+21'
+);
+assert.strictEqual(
+  util.format('%d', 1180591620717411303424n),
+  '1180591620717411303424n'
+);
 
 // Integer format specifier
 assert.strictEqual(util.format('%i'), '%i');