perf: optimize logger (#15574)

packages/vite/src/node/logger.ts

@@ -51,6 +51,18 @@ export interface LoggerOptions {
   customLogger?: Logger
 }
 
+// Only initialize the timeFormatter when the timestamp option is used, and
+// reuse it across all loggers
+let timeFormatter: Intl.DateTimeFormat
+function getTimeFormatter() {
+  timeFormatter ??= new Intl.DateTimeFormat(undefined, {
+    hour: 'numeric',
+    minute: 'numeric',
+    second: 'numeric',
+  })
+  return timeFormatter
+}
+
 export function createLogger(
   level: LogLevel = 'info',
   options: LoggerOptions = {},
@@ -59,53 +71,55 @@ export function createLogger(
     return options.customLogger
   }
 
-  const timeFormatter = new Intl.DateTimeFormat(undefined, {
-    hour: 'numeric',
-    minute: 'numeric',
-    second: 'numeric',
-  })
   const loggedErrors = new WeakSet<Error | RollupError>()
   const { prefix = '[vite]', allowClearScreen = true } = options
   const thresh = LogLevels[level]
   const canClearScreen =
     allowClearScreen && process.stdout.isTTY && !process.env.CI
   const clear = canClearScreen ? clearScreen : () => {}
 
+  function format(type: LogType, msg: string, options: LogErrorOptions = {}) {
+    if (options.timestamp) {
+      const tag =
+        type === 'info'
+          ? colors.cyan(colors.bold(prefix))
+          : type === 'warn'
+            ? colors.yellow(colors.bold(prefix))
+            : colors.red(colors.bold(prefix))
+      return `${colors.dim(
+        getTimeFormatter().format(new Date()),
+      )} ${tag} ${msg}`
+    } else {
+      return msg
+    }
+  }
+
   function output(type: LogType, msg: string, options: LogErrorOptions = {}) {
     if (thresh >= LogLevels[type]) {
       const method = type === 'info' ? 'log' : type
-      const format = () => {
-        if (options.timestamp) {
-          const tag =
-            type === 'info'
-              ? colors.cyan(colors.bold(prefix))
-              : type === 'warn'
-                ? colors.yellow(colors.bold(prefix))
-                : colors.red(colors.bold(prefix))
-          return `${colors.dim(timeFormatter.format(new Date()))} ${tag} ${msg}`
-        } else {
-          return msg
-        }
-      }
+
       if (options.error) {
         loggedErrors.add(options.error)
       }
       if (canClearScreen) {
         if (type === lastType && msg === lastMsg) {
           sameCount++
           clear()
-          console[method](format(), colors.yellow(`(x${sameCount + 1})`))
+          console[method](
+            format(type, msg, options),
+            colors.yellow(`(x${sameCount + 1})`),
+          )
         } else {
           sameCount = 0
           lastMsg = msg
           lastType = type
           if (options.clear) {
             clear()
           }
-          console[method](format())
+          console[method](format(type, msg, options))
         }
       } else {
-        console[method](format())
+        console[method](format(type, msg, options))
       }
     }
   }