Limits of stringify

src/deepCopy.js

@@ -1,11 +1,13 @@
+const v8 = require('v8'); // Node v11 and onwards
+
 /**
  * A function to deeply copy an object
  * (circular references will break it).
  * @param {(Object | Array)} o - The object or array you want to copy
  * @return {(Object | Array)} - The new, cloned object or array
  */
 const deepCopy = (o) => {
-  return JSON.parse(JSON.stringify(o));
+    return v8.deserialize(v8.serialize(o));
 };
 
 module.exports = deepCopy;

src/tests/deepCopy.test.js

@@ -18,4 +18,31 @@ describe("deepCopy", () => {
     expect(newObj.name.first).to.equal("Alpha");
     expect(myObj.name.first).to.equal("Bravo");
   });
+  it("can copy an object that has arrays as values", () => {
+    const myObj = {
+      a: [1],
+      }
+    const newObj = deepCopy(myObj);
+    expect(newObj.a).to.deep.equal(myObj.a);
+  });
+  it("can copy an object that has undefined, NaN, Infinity as values", () => {
+    const myObj = {
+      a: [1],
+      b: new Date(),
+      c: undefined,
+      d: Infinity,
+      e: NaN,
+      f: false,
+      }
+    const newObj = deepCopy(myObj);
+    expect(newObj.a).to.deep.equal(myObj.a);
+    expect(newObj.b).to.deep.equal(myObj.b);
+    expect(newObj.c).to.equal(myObj.c);
+    expect(newObj.d).to.equal(myObj.d);
+    expect(newObj.e).to.not.equal(newObj.e); // test for NaN being copied over
+    // > NaN !== NaN
+    //true
+    expect(newObj.f).to.equal(myObj.f);
+  });
+
 });