Use const rather than let, as always

[JaeYeopHan]

❌ Hey, What's the matter?

function calculate() {
  let arrayOrString = somethingFunc();
  let isArray = Array.isArray(arrayOrString)

  if (isArray) {
    console.log(typeof arrayOrString) // string | object (array) 💥
    // isn't array?
  }
}

Come back to const!

-  let arrayOrString = somethingFunc();
+  const arrayOrString = somethingFunc();
-  let isArray = Array.isArray(arrayOrString)
+  const isArray = Array.isArray(arrayOrString)

so,

✅ That's right

function calculate() {
  const arrayOrString = somethingFunc();
  const isArray = Array.isArray(arrayOrString)

  if (isArray) {
-    console.log(typeof arrayOrString) // string | object (array)
+    console.log(typeof arrayOrString) // object (array) 🥰
  }
}

[brightparagon]

어찌 이런 일이..