Split jslib into multiple modules (#363)

* Split jslib into multiple modules

common/src/misc/nodeUtils.ts

@@ -0,0 +1,34 @@
+import * as fs from 'fs';
+import * as path from 'path';
+import * as readline from 'readline';
+
+export class NodeUtils {
+    static mkdirpSync(targetDir: string, mode = '700', relative = false, relativeDir: string = null) {
+        const initialDir = path.isAbsolute(targetDir) ? path.sep : '';
+        const baseDir = relative ? (relativeDir != null ? relativeDir : __dirname) : '.';
+        targetDir.split(path.sep).reduce((parentDir, childDir) => {
+            const dir = path.resolve(baseDir, parentDir, childDir);
+            if (!fs.existsSync(dir)) {
+                fs.mkdirSync(dir, mode);
+            }
+            return dir;
+        }, initialDir);
+    }
+    static readFirstLine(fileName: string) {
+        return new Promise<string>((resolve, reject) => {
+            const readStream = fs.createReadStream(fileName, {encoding: 'utf8'});
+            const readInterface = readline.createInterface(readStream);
+            readInterface
+                .on('line', line => {
+                    readStream.close();
+                    resolve(line);
+                })
+                .on('error', err => reject(err));
+        });
+    }
+
+    // https://stackoverflow.com/a/31394257
+    static bufferToArrayBuffer(buf: Buffer): ArrayBuffer {
+        return buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength);
+    }
+}