Added Log File Utility #39

libraries/js/logsmith/lib/logFileUtility.js

@@ -0,0 +1,41 @@
+import * as filesystem from 'fs'
+import ndjson from 'ndjson'
+
+function createLogFileIfNotExists(filepath) {
+    filesystem.writeFileSync(filepath, "", function (err) {
+        if (err) console.error(err);
+    })
+}
+
+// To Do: add try-catch block and callback(err) on failure
+export function writeLogToFile(log, filepath, consoleOnly) {
+    if (consoleOnly) {
+        return
+    }
+    if (!filesystem.existsSync(filepath)) {
+        createLogFileIfNotExists(filepath)
+    }
+    const stream = ndjson.stringify()
+    stream.on('data', function (logline) {
+        filesystem.appendFileSync(filepath, logline);
+    })
+    stream.write(log)
+    stream.end()
+}
+
+export function writeLogToFileOnExit(logs, filepath, consoleOnly) {
+    if (consoleOnly) {
+        return
+    }
+    if (!filesystem.existsSync(filepath)) {
+        createLogFileIfNotExists(filepath)
+    }
+    const stream = ndjson.stringify()
+    stream.on('data', function (logline) {
+        filesystem.appendFileSync(filepath, logline);
+    })
+    logs.forEach(logline => {
+        stream.write(logline)
+    });
+    stream.end()
+}