nginx-iteractive-index: Reimplement humanFileSize

The previous implementation was copy-pasted from a source that did not
allow redistribution or sublicensing. Therefore, I reimplemented the
function myself.

modules/nginx-interactive-index/listing.js

@@ -1,19 +1,17 @@
 document.addEventListener('DOMContentLoaded', () => {
-  function humanFileSize(bytes) {
-      const thresh = 1024
-      if(Math.abs(bytes) < thresh) {
-          return bytes + ' B'
-      }
-      const units = ['KiB','MiB','GiB','TiB','PiB','EiB','ZiB','YiB']
-      var u = -1
-      do {
-          bytes /= thresh
-          ++u
-      } while(Math.abs(bytes) >= thresh && u < units.length - 1)
-      return bytes.toFixed(1)+' '+units[u]
+  function humanFileSize(size) {
+    if (size === 0) {
+      return "0 B";
+    }
+    if (size < 0) {
+      return null;
+    }
+    const base = Math.floor(Math.log2(size) / 10)
+    const unit = ["B", "KiB", "MiB", "GiB", "TiB"][base]
+    const relative = size / 2**(10*base)
+    return relative.toFixed(3) + " " + unit
   }
 
-
   function textToA(line) {
     let outerElement = document.createElement('div')
     outerElement.innerHTML = line