feature: root option allows array of strings

src/util/fs.js

@@ -0,0 +1,34 @@
+const fs = require('fs');
+
+function readFileAsync(filepath) {
+    return new Promise(function(resolve, reject) {
+        fs.readFile(filepath, 'utf8', function(err, content) {
+            err ? reject(err) : resolve(content);
+        });
+    });
+};
+
+function statFileAsync(path) {
+    return new Promise(function(resolve, reject) {
+        fs.stat(path, (err, stat) => err ? reject(err) : resolve(stat))
+    });
+};
+
+function pathResolve(root, path) {
+    if (path[0] == '/') return path;
+
+    var arr = root.split('/').concat(path.split('/'));
+    var result = [];
+    arr.forEach(function(slug) {
+        if (slug == '..') result.pop();
+        else if (!slug || slug == '.');
+        else result.push(slug);
+    });
+    return '/' + result.join('/');
+}
+
+module.exports = {
+    readFileAsync,
+    pathResolve,
+    statFileAsync
+};