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30-seconds-of-code/snippets/prettyBytes.md
Angelos Chalaris 00b3da7504 Updated examples
Removed duplicate and unnecessary examples.
2018-01-04 14:22:56 +02:00

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### prettyBytes
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.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
```