Add %J console format specifier

doc/api/util.md

@@ -236,6 +236,7 @@ corresponding argument. Supported specifiers are:
 * `%f`: `parseFloat(value)` is used for all values expect `Symbol`.
 * `%j`: JSON. Replaced with the string `'[Circular]'` if the argument contains
   circular references.
+* `%J`: Indented version of %j.
 * `%o`: `Object`. A string representation of an object with generic JavaScript
   object formatting. Similar to `util.inspect()` with options
   `{ showHidden: true, showProxy: true }`. This will show the full object

lib/internal/util/inspect.js

@@ -1770,14 +1770,14 @@ function hasBuiltInToString(value) {
 
 const firstErrorLine = (error) => error.message.split('\n')[0];
 let CIRCULAR_ERROR_MESSAGE;
-function tryStringify(arg) {
+function tryStringify(arg, indentation = 0) {
   try {
-    return JSONStringify(arg);
+    return JSONStringify(arg, null, indentation);
   } catch (err) {
     // Populate the circular error message lazily
     if (!CIRCULAR_ERROR_MESSAGE) {
       try {
-        const a = {}; a.a = a; JSONStringify(a);
+        const a = {}; a.a = a; JSONStringify(a, null, indentation);
       } catch (err) {
         CIRCULAR_ERROR_MESSAGE = firstErrorLine(err);
       }
@@ -1842,6 +1842,9 @@ function formatWithOptionsInternal(inspectOptions, ...args) {
             case 106: // 'j'
               tempStr = tryStringify(args[++a]);
               break;
+            case 74: // 'J'
+              tempStr = tryStringify(args[++a], 2);
+              break;
             case 100: // 'd'
               const tempNum = args[++a];
               if (typeof tempNum === 'bigint') {

test/parallel/test-util-format.js

@@ -44,6 +44,7 @@ assert.strictEqual(util.format(symbol), 'Symbol(foo)');
 assert.strictEqual(util.format('foo', symbol), 'foo Symbol(foo)');
 assert.strictEqual(util.format('%s', symbol), 'Symbol(foo)');
 assert.strictEqual(util.format('%j', symbol), 'undefined');
+assert.strictEqual(util.format('%J', symbol), 'undefined');
 
 // Number format specifier
 assert.strictEqual(util.format('%d'), '%d');
@@ -237,6 +238,16 @@ assert.strictEqual(util.format('%j', '42'), '"42"');
 assert.strictEqual(util.format('%j %j', 42, 43), '42 43');
 assert.strictEqual(util.format('%j %j', 42), '42 %j');
 
+// Indented JSON format specifier
+assert.strictEqual(util.format('%J'), '%J');
+assert.strictEqual(util.format('%J', 42), '42');
+assert.strictEqual(util.format('%J', '42'), '"42"');
+assert.strictEqual(util.format('%J %J', 42, 43), '42 43');
+assert.strictEqual(util.format('%J %J', 42), '42 %J');
+assert.strictEqual(
+  util.format('%J', { foo: { bar: 42 } })
+  , '{\n  "foo": {\n    "bar": 42\n  }\n}');
+
 // Object format specifier
 const obj = {
   foo: 'bar',

test/pummel/test-child-process-spawn-loop.js

@@ -30,7 +30,7 @@ const N = 40;
 let finished = false;
 
 function doSpawn(i) {
-  const child = spawn('python', ['-c', `print ${SIZE} * "C"`]);
+  const child = spawn('python', ['-c', `print(${SIZE} * "C")`]);
   let count = 0;
 
   child.stdout.setEncoding('ascii');