node.js的hello world项目。
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# Bytes utility
[![NPM Version][npm-image]][npm-url]
[![NPM Downloads][downloads-image]][downloads-url]
[![Build Status][ci-image]][ci-url]
[![Test Coverage][coveralls-image]][coveralls-url]
Utility to parse a string bytes (ex: `1TB`) to bytes (`1099511627776`) and vice-versa.
## Installation
This is a [Node.js](https://nodejs.org/en/) module available through the
[npm registry](https://www.npmjs.com/). Installation is done using the
[`npm install` command](https://docs.npmjs.com/getting-started/installing-npm-packages-locally):
```bash
$ npm install bytes
```
## Usage
```js
var bytes = require('bytes');
```
#### bytes(number|string value, [options]): number|string|null
Default export function. Delegates to either `bytes.format` or `bytes.parse` based on the type of `value`.
**Arguments**
| Name | Type | Description |
|---------|----------|--------------------|
| value | `number`|`string` | Number value to format or string value to parse |
| options | `Object` | Conversion options for `format` |
**Returns**
| Name | Type | Description |
|---------|------------------|-------------------------------------------------|
| results | `string`|`number`|`null` | Return null upon error. Numeric value in bytes, or string value otherwise. |
**Example**
```js
bytes(1024);
// output: '1KB'
bytes('1KB');
// output: 1024
```
#### bytes.format(number value, [options]): string|null
Format the given value in bytes into a string. If the value is negative, it is kept as such. If it is a float, it is
rounded.
**Arguments**
| Name | Type | Description |
|---------|----------|--------------------|
| value | `number` | Value in bytes |
| options | `Object` | Conversion options |
**Options**
| Property | Type | Description |
|-------------------|--------|-----------------------------------------------------------------------------------------|
| decimalPlaces | `number`|`null` | Maximum number of decimal places to include in output. Default value to `2`. |
| fixedDecimals | `boolean`|`null` | Whether to always display the maximum number of decimal places. Default value to `false` |
| thousandsSeparator | `string`|`null` | Example of values: `' '`, `','` and `'.'`... Default value to `''`. |
| unit | `string`|`null` | The unit in which the result will be returned (B/KB/MB/GB/TB). Default value to `''` (which means auto detect). |
| unitSeparator | `string`|`null` | Separator to use between number and unit. Default value to `''`. |
**Returns**
| Name | Type | Description |
|---------|------------------|-------------------------------------------------|
| results | `string`|`null` | Return null upon error. String value otherwise. |
**Example**
```js
bytes.format(1024);
// output: '1KB'
bytes.format(1000);
// output: '1000B'
bytes.format(1000, {thousandsSeparator: ' '});
// output: '1 000B'
bytes.format(1024 * 1.7, {decimalPlaces: 0});
// output: '2KB'
bytes.format(1024, {unitSeparator: ' '});
// output: '1 KB'
```
#### bytes.parse(string|number value): number|null
Parse the string value into an integer in bytes. If no unit is given, or `value`
is a number, it is assumed the value is in bytes.
Supported units and abbreviations are as follows and are case-insensitive:
* `b` for bytes
* `kb` for kilobytes
* `mb` for megabytes
* `gb` for gigabytes
* `tb` for terabytes
* `pb` for petabytes
The units are in powers of two, not ten. This means 1kb = 1024b according to this parser.
**Arguments**
| Name | Type | Description |
|---------------|--------|--------------------|
| value | `string`|`number` | String to parse, or number in bytes. |
**Returns**
| Name | Type | Description |
|---------|-------------|-------------------------|
| results | `number`|`null` | Return null upon error. Value in bytes otherwise. |
**Example**
```js
bytes.parse('1KB');
// output: 1024
bytes.parse('1024');
// output: 1024
bytes.parse(1024);
// output: 1024
```
## License
[MIT](LICENSE)
[ci-image]: https://badgen.net/github/checks/visionmedia/bytes.js/master?label=ci
[ci-url]: https://github.com/visionmedia/bytes.js/actions?query=workflow%3Aci
[coveralls-image]: https://badgen.net/coveralls/c/github/visionmedia/bytes.js/master
[coveralls-url]: https://coveralls.io/r/visionmedia/bytes.js?branch=master
[downloads-image]: https://badgen.net/npm/dm/bytes
[downloads-url]: https://npmjs.org/package/bytes
[npm-image]: https://badgen.net/npm/v/bytes
[npm-url]: https://npmjs.org/package/bytes