No Watching

src/compiler/watch.ts

@@ -233,13 +233,14 @@ namespace ts {
     }
 
     export const noopFileWatcher: FileWatcher = { close: noop };
+    export const returnNoopFileWatcher = () => noopFileWatcher;
 
     export function createWatchHost(system = sys, reportWatchStatus?: WatchStatusReporter): WatchHost {
         const onWatchStatusChange = reportWatchStatus || createWatchStatusReporter(system);
         return {
             onWatchStatusChange,
-            watchFile: maybeBind(system, system.watchFile) || (() => noopFileWatcher),
-            watchDirectory: maybeBind(system, system.watchDirectory) || (() => noopFileWatcher),
+            watchFile: maybeBind(system, system.watchFile) || returnNoopFileWatcher,
+            watchDirectory: maybeBind(system, system.watchDirectory) || returnNoopFileWatcher,
             setTimeout: maybeBind(system, system.setTimeout) || noop,
             clearTimeout: maybeBind(system, system.clearTimeout) || noop
         };

src/server/editorServices.ts

@@ -724,7 +724,13 @@ namespace ts.server {
             const watchLogLevel = this.logger.hasLevel(LogLevel.verbose) ? WatchLogLevel.Verbose :
                 this.logger.loggingEnabled() ? WatchLogLevel.TriggerOnly : WatchLogLevel.None;
             const log: (s: string) => void = watchLogLevel !== WatchLogLevel.None ? (s => this.logger.info(s)) : noop;
-            this.watchFactory = getWatchFactory(watchLogLevel, log, getDetailWatchInfo);
+            this.watchFactory = this.syntaxOnly ?
+                {
+                    watchFile: returnNoopFileWatcher,
+                    watchFilePath: returnNoopFileWatcher,
+                    watchDirectory: returnNoopFileWatcher,
+                } :
+                getWatchFactory(watchLogLevel, log, getDetailWatchInfo);
         }
 
         toPath(fileName: string) {

src/server/project.ts

@@ -947,7 +947,7 @@ namespace ts.server {
 
             // update builder only if language service is enabled
             // otherwise tell it to drop its internal state
-            if (this.languageServiceEnabled) {
+            if (this.languageServiceEnabled && !this.projectService.syntaxOnly) {
                 // 1. no changes in structure, no changes in unresolved imports - do nothing
                 // 2. no changes in structure, unresolved imports were changed - collect unresolved imports for all files
                 // (can reuse cached imports for files that were not changed)
@@ -1070,7 +1070,7 @@ namespace ts.server {
                 }
 
                 // Watch the type locations that would be added to program as part of automatic type resolutions
-                if (this.languageServiceEnabled) {
+                if (this.languageServiceEnabled && !this.projectService.syntaxOnly) {
                     this.resolutionCache.updateTypeRootsWatch();
                 }
             }