check for NaN, as NaN === "number" evaluates to true.

RaihanSharif · RaihanSharif · commit ef50a5870b34 · 2026-05-07T17:56:18.000+01:00
diff --git a/Sprint-1/implement/sum.js b/Sprint-1/implement/sum.js
@@ -1,6 +1,6 @@
 function sum(elements) {
   return elements.reduce((acc, curr) => {
-    if (typeof curr !== "number") {
+    if (typeof curr !== "number" || isNaN(curr)) {
       return acc;
     }
     return acc + curr;

Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`	`function sum(elements) {`
`2`	`2`	`return elements.reduce((acc, curr) => {`
`3`		`- if (typeof curr !== "number") {`
	`3`	`+ if (typeof curr !== "number" \|\| isNaN(curr)) {`
`4`	`4`	`return acc;`
`5`	`5`	`}`
`6`	`6`	`return acc + curr;`