transition from javascript to typescript

assets/ts/indexDisp.ts

@@ -0,0 +1,17 @@
+import { duper } from './utils'
+
+// update index of displaying image
+export function imgIndexSpanUpdate(numOne: number, numTwo: number): void {
+  // footer index number display module
+  const footerIndexDisp = document.getElementsByClassName('ftid')
+  const numOneString: string = duper(numOne)
+  const numTwoString: string = duper(numTwo)
+  for (let i: number = 0; i <= 7; i++) {
+    const footerIndex = footerIndexDisp[i] as HTMLSpanElement
+    if (i > 3) {
+      footerIndex.innerText = numTwoString[i - 4]
+    } else {
+      footerIndex.innerText = numOneString[i]
+    }
+  }
+}