util: add Temporal support to inspect()

Signed-off-by: Renegade334 <contact.9a5d6388@renegade334.me.uk>

Author: Renegade334

lib/internal/util/inspect.js

@@ -208,6 +208,40 @@ function isURL(value) {
   return typeof value.href === 'string' && value instanceof internalUrl.URL;
 }
 
+const temporalConstructors = [
+  { name: 'Duration', fullName: 'Temporal.Duration' },
+  { name: 'Instant', fullName: 'Temporal.Instant' },
+  { name: 'PlainDate', fullName: 'Temporal.PlainDate' },
+  { name: 'PlainDateTime', fullName: 'Temporal.PlainDateTime' },
+  { name: 'PlainMonthDay', fullName: 'Temporal.PlainMonthDay' },
+  { name: 'PlainTime', fullName: 'Temporal.PlainTime' },
+  { name: 'PlainYearMonth', fullName: 'Temporal.PlainYearMonth' },
+  { name: 'ZonedDateTime', fullName: 'Temporal.ZonedDateTime' },
+];
+
+// Best-effort, using instanceof. Polyfills will likely pass these checks.
+// TODO: Hopefully the V8 API will expose typechecks at some point.
+function getTemporalInfo(value) {
+  try {
+    const { Temporal } = globalThis;
+    if (Temporal != null) {
+      for (let i = 0; i < temporalConstructors.length; i++) {
+        const entry = temporalConstructors[i];
+        const constructor = Temporal[entry.name];
+        if (typeof constructor !== 'function' || !FunctionPrototypeSymbolHasInstance(constructor, value)) {
+          continue;
+        }
+        const { prototype } = constructor;
+        if (!ObjectPrototypeHasOwnProperty(prototype, 'toString')) {
+          return;
+        }
+        const result = FunctionPrototypeCall(prototype.toString, value);
+        return { ...entry, result };
+      }
+    }
+  } catch { /* void */ }
+}
+
 const builtInObjects = new SafeSet(
   ArrayPrototypeFilter(
     ObjectGetOwnPropertyNames(globalThis),
@@ -1321,6 +1355,7 @@ function formatRaw(ctx, value, recurseTimes, typedArray) {
   if (noIterator) {
     keys = getKeys(value, ctx.showHidden);
     braces = ['{', '}'];
+    let temporalInfo;
     if (typeof value === 'function') {
       base = getFunctionBase(ctx, value, constructor, tag);
       if (keys.length === 0 && protoProps === undefined)
@@ -1404,6 +1439,14 @@ function formatRaw(ctx, value, recurseTimes, typedArray) {
       if (keys.length === 0 && protoProps === undefined) {
         return base;
       }
+    } else if ((temporalInfo = getTemporalInfo(value))) {
+      const prefix = constructor === temporalInfo.name && tag === temporalInfo.fullName ?
+        (temporalInfo.fullName + ' ') :
+        getPrefix(constructor, tag, temporalInfo.fullName);
+      base = `${prefix}${temporalInfo.result}`;
+      if (keys.length === 0 && protoProps === undefined) {
+        return ctx.stylize(base, 'date');
+      }
     } else {
       if (keys.length === 0 && protoProps === undefined) {
         if (isExternal(value)) {