Rename js snippets

snippets/js/s/pretty-print-number-of-bytes.md

@@ -0,0 +1,37 @@
+---
+title: Pretty-print number of bytes
+type: snippet
+language: javascript
+tags: [string,math]
+cover: digital-nomad
+dateModified: 2020-10-22T20:24:04+03:00
+---
+
+Converts a number in bytes to a human-readable string.
+
+- Use an array dictionary of units to be accessed based on the exponent.
+- Use `Number.prototype.toPrecision()` to truncate the number to a certain number of digits.
+- Return the prettified string by building it up, taking into account the supplied options and whether it is negative or not.
+- Omit the second argument, `precision`, to use a default precision of `3` digits.
+- Omit the third argument, `addSpace`, to add space between the number and unit by default.
+
+```js
+const prettyBytes = (num, precision = 3, addSpace = true) => {
+  const UNITS = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
+  if (Math.abs(num) < 1) return num + (addSpace ? ' ' : '') + UNITS[0];
+  const exponent = Math.min(
+    Math.floor(Math.log10(num < 0 ? -num : num) / 3),
+    UNITS.length - 1
+  );
+  const n = Number(
+    ((num < 0 ? -num : num) / 1000 ** exponent).toPrecision(precision)
+  );
+  return (num < 0 ? '-' : '') + n + (addSpace ? ' ' : '') + UNITS[exponent];
+};
+```
+
+```js
+prettyBytes(1000); // '1 KB'
+prettyBytes(-27145424323.5821, 5); // '-27.145 GB'
+prettyBytes(123456789, 3, false); // '123MB'
+```