mirror of
https://github.com/idanoo/GoScrobble.git
synced 2024-11-28 03:15:16 +00:00
97 lines
3.3 KiB
Markdown
97 lines
3.3 KiB
Markdown
# json-parse-even-better-errors
|
|
|
|
[`json-parse-even-better-errors`](https://github.com/npm/json-parse-even-better-errors)
|
|
is a Node.js library for getting nicer errors out of `JSON.parse()`,
|
|
including context and position of the parse errors.
|
|
|
|
It also preserves the newline and indentation styles of the JSON data, by
|
|
putting them in the object or array in the `Symbol.for('indent')` and
|
|
`Symbol.for('newline')` properties.
|
|
|
|
## Install
|
|
|
|
`$ npm install --save json-parse-even-better-errors`
|
|
|
|
## Table of Contents
|
|
|
|
* [Example](#example)
|
|
* [Features](#features)
|
|
* [Contributing](#contributing)
|
|
* [API](#api)
|
|
* [`parse`](#parse)
|
|
|
|
### Example
|
|
|
|
```javascript
|
|
const parseJson = require('json-parse-even-better-errors')
|
|
|
|
parseJson('"foo"') // returns the string 'foo'
|
|
parseJson('garbage') // more useful error message
|
|
parseJson.noExceptions('garbage') // returns undefined
|
|
```
|
|
|
|
### Features
|
|
|
|
* Like JSON.parse, but the errors are better.
|
|
* Strips a leading byte-order-mark that you sometimes get reading files.
|
|
* Has a `noExceptions` method that returns undefined rather than throwing.
|
|
* Attaches the newline character(s) used to the `Symbol.for('newline')`
|
|
property on objects and arrays.
|
|
* Attaches the indentation character(s) used to the `Symbol.for('indent')`
|
|
property on objects and arrays.
|
|
|
|
## Indentation
|
|
|
|
To preserve indentation when the file is saved back to disk, use
|
|
`data[Symbol.for('indent')]` as the third argument to `JSON.stringify`, and
|
|
if you want to preserve windows `\r\n` newlines, replace the `\n` chars in
|
|
the string with `data[Symbol.for('newline')]`.
|
|
|
|
For example:
|
|
|
|
```js
|
|
const txt = await readFile('./package.json', 'utf8')
|
|
const data = parseJsonEvenBetterErrors(txt)
|
|
const indent = Symbol.for('indent')
|
|
const newline = Symbol.for('newline')
|
|
// .. do some stuff to the data ..
|
|
const string = JSON.stringify(data, null, data[indent]) + '\n'
|
|
const eolFixed = data[newline] === '\n' ? string
|
|
: string.replace(/\n/g, data[newline])
|
|
await writeFile('./package.json', eolFixed)
|
|
```
|
|
|
|
Indentation is determined by looking at the whitespace between the initial
|
|
`{` and `[` and the character that follows it. If you have lots of weird
|
|
inconsistent indentation, then it won't track that or give you any way to
|
|
preserve it. Whether this is a bug or a feature is debatable ;)
|
|
|
|
### API
|
|
|
|
#### <a name="parse"></a> `parse(txt, reviver = null, context = 20)`
|
|
|
|
Works just like `JSON.parse`, but will include a bit more information when
|
|
an error happens, and attaches a `Symbol.for('indent')` and
|
|
`Symbol.for('newline')` on objects and arrays. This throws a
|
|
`JSONParseError`.
|
|
|
|
#### <a name="parse"></a> `parse.noExceptions(txt, reviver = null)`
|
|
|
|
Works just like `JSON.parse`, but will return `undefined` rather than
|
|
throwing an error.
|
|
|
|
#### <a name="jsonparseerror"></a> `class JSONParseError(er, text, context = 20, caller = null)`
|
|
|
|
Extends the JavaScript `SyntaxError` class to parse the message and provide
|
|
better metadata.
|
|
|
|
Pass in the error thrown by the built-in `JSON.parse`, and the text being
|
|
parsed, and it'll parse out the bits needed to be helpful.
|
|
|
|
`context` defaults to 20.
|
|
|
|
Set a `caller` function to trim internal implementation details out of the
|
|
stack trace. When calling `parseJson`, this is set to the `parseJson`
|
|
function. If not set, then the constructor defaults to itself, so the
|
|
stack trace will point to the spot where you call `new JSONParseError`.
|