26 lines
685 B
Markdown
26 lines
685 B
Markdown
---
|
|
title: Reverse number
|
|
tags: math,string
|
|
cover: walking
|
|
firstSeen: 2020-07-17T16:41:28+03:00
|
|
lastUpdated: 2020-09-18T21:19:23+03:00
|
|
---
|
|
|
|
Reverses a number.
|
|
|
|
- Use `Object.prototype.toString()` to convert `n` to a string.
|
|
- Use `String.prototype.split()`, `Array.prototype.reverse()` and `Array.prototype.join()` to get the reversed value of `n` as a string.
|
|
- Use `parseFloat()` to convert the string to a number and `Math.sign()` to preserve its sign.
|
|
|
|
```js
|
|
const reverseNumber = n =>
|
|
parseFloat(`${n}`.split('').reverse().join('')) * Math.sign(n);
|
|
```
|
|
|
|
```js
|
|
reverseNumber(981); // 189
|
|
reverseNumber(-500); // -5
|
|
reverseNumber(73.6); // 6.37
|
|
reverseNumber(-5.23); // -32.5
|
|
```
|