ok

1-js/4-object-basics/05-constructor-new/4-calculator-extendable/_js.view/solution.js

@@ -0,0 +1,29 @@
+function Calculator() {
+
+  var methods = {
+    "-": function(a, b) {
+      return a - b;
+    },
+    "+": function(a, b) {
+      return a + b;
+    }
+  };
+
+  this.calculate = function(str) {
+
+    var split = str.split(' '),
+      a = +split[0],
+      op = split[1],
+      b = +split[2]
+
+    if (!methods[op] || isNaN(a) || isNaN(b)) {
+      return NaN;
+    }
+
+    return methods[op](a, b);
+  }
+
+  this.addMethod = function(name, func) {
+    methods[name] = func;
+  };
+}