feat(eval): handle globals

packages/bruno-js/src/utils.js

@@ -26,14 +26,26 @@ const compileJsExpression = (expr) => {
   const matches = expr.match(/([\w\.$]+)/g) ?? [];
 
   // get valid js identifiers (foo, bar)
-  const names = matches
+  const vars = new Set(
-    .filter(match => /^[a-zA-Z$_]/.test(match))
+    matches
-    .map(match => match.split('.')[0]);
+      .filter(match => /^[a-zA-Z$_]/.test(match))   // starts with valid js identifier (foo.bar)
+      .map(match => match.split('.')[0])            // top level identifier (foo)
+      .filter(name => !JS_KEYWORDS.includes(name))  // exclude js keywords
+  );
+
+  // globals such as Math
+  const globals = [...vars].filter(name => name in globalThis);
+
+  const code = {
+    vars: [...vars].join(", "),
+    // pick global from context or globalThis
+    globals: globals
+      .map(name => ` ${name} = ${name} ?? globalThis.${name};`)
+      .join('')
+  };
+
+  const body = `let { ${code.vars} } = context; ${code.globals}; return ${expr}`;
 
-  // exclude js keywords and get unique vars
-  const vars = new Set(names.filter(name => !JS_KEYWORDS.includes(name)));
-  const spread = [...vars].join(", ");
-  const body = `const { ${spread} } = context; return ${expr}`;
   return new Function("context", body);
 };
 

packages/bruno-js/tests/utils.spec.js

@@ -44,32 +44,32 @@ describe("utils", () => {
     it("should identify top level variables", () => {
       const expr = "res.data.pets[0].toUpperCase()";
       evaluateJsExpression(expr, context);
-      expect(cache.get(expr).toString()).toContain("const { res } = context;");
+      expect(cache.get(expr).toString()).toContain("let { res } = context;");
     });
 
     it("should not duplicate variables", () => {
       const expr = "res.data.pets[0] + res.data.pets[1]";
       evaluateJsExpression(expr, context);
-      expect(cache.get(expr).toString()).toContain("const { res } = context;");
+      expect(cache.get(expr).toString()).toContain("let { res } = context;");
     });
 
     it("should exclude js keywords like true false from vars", () => {
       const expr = "res.data.pets.length > 0 ? true : false";
       evaluateJsExpression(expr, context);
-      expect(cache.get(expr).toString()).toContain("const { res } = context;");
+      expect(cache.get(expr).toString()).toContain("let { res } = context;");
     });
 
     it("should exclude numbers from vars", () => {
       const expr = "res.data.pets.length + 10";
       evaluateJsExpression(expr, context);
-      expect(cache.get(expr).toString()).toContain("const { res } = context;");
+      expect(cache.get(expr).toString()).toContain("let { res } = context;");
     });
 
     it("should pick variables from complex expressions", () => {
       const expr = "res.data.pets.map(pet => pet.length)";
       const result = evaluateJsExpression(expr, context);
       expect(result).toEqual([5, 3]);
-      expect(cache.get(expr).toString()).toContain("const { res, pet } = context;");
+      expect(cache.get(expr).toString()).toContain("let { res, pet } = context;");
     });
 
     it("should be ok picking extra vars from strings", () => {
@@ -77,7 +77,39 @@ describe("utils", () => {
       const result = evaluateJsExpression(expr, context);
       expect(result).toBe("hello bruno");
       // extra var hello is harmless
-      expect(cache.get(expr).toString()).toContain("const { hello, res } = context;");
+      expect(cache.get(expr).toString()).toContain("let { hello, res } = context;");
+    });
+
+    it("should evaluate expressions referencing globals", () => {
+      const startTime = new Date("2022-02-01").getTime();
+      const currentTime = new Date("2022-02-02").getTime();
+
+      jest.useFakeTimers({ now: currentTime });
+
+      const expr = "Math.max(Date.now(), startTime)";
+      const result = evaluateJsExpression(expr, { startTime });
+
+      expect(result).toBe(currentTime);
+
+      expect(cache.get(expr).toString()).toContain("Math = Math ?? globalThis.Math;");
+      expect(cache.get(expr).toString()).toContain("Date = Date ?? globalThis.Date;");
+    });
+
+    it("should use global overridden in context", () => {
+      const startTime = new Date("2022-02-01").getTime();
+      const currentTime = new Date("2022-02-02").getTime();
+
+      jest.useFakeTimers({ now: currentTime });
+
+      const context = {
+        Date: { now: () => new Date("2022-01-31").getTime() },
+        startTime
+      };
+
+      const expr = "Math.max(Date.now(), startTime)";
+      const result = evaluateJsExpression(expr, context);
+
+      expect(result).toBe(startTime);
     });
   });
 });