Package Exports

@expo/json-file

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (@expo/json-file) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

json-file

A module for reading, writing, and manipulating JSON files

Importing the package

import JsonFile from '@exponent/json-file';

Promise-based async API

Everything returns Promises. If you are using ES7 (or Babel), you can write code like this:

let config = await JsonFile.readAsync('config.json', {cantReadFileDefault: {}});

If you are using ES6, you can just use the return values the way you normally would use Promises.

JsonFile.readAsync('config.json', {cantReadFileDefault: {}}).then(config => {
   ...
});

Used as an object

var file = new JsonFile('config.json', {cantReadFileDefault: {}});
var somethingSaved = await file.getAsync('somethingSaved', null);

Used as functions

var pkg = await JsonFile.readAsync('package.json');
var main = await JsonFile.getAsync('package.json', 'main', 'index.js');
...

Options you can set, and their default values

Option	Description	Default Value
`space`	How many spaces to use when pretty-printing, (0 for no pretty-printing)	`2`
`default`	Catch-all default value for missing values, bad JSON, and files that can't be read	`undefined`
`jsonParseErrorDefault`	The default value for when a file is read but it doesn't contain valid JSON	`undefined`
`cantReadFileDefault`	The default value for when a file can't be read	`undefined`

Note that if defaults are undefined, then an Error will be thrown instead of undefined being returned

Methods

.readAsync([options])

Returns the parse of the whole file as an object

.getAsync(key, [default-value], [options])

Returns a single value from a JSON file, using lodash's _.get to query the whole object.

See https://lodash.com/docs#get

.writeAsync(data, [options])

Writes out the given data to the file

.setAsync(key, val, [options])

Updates the file, inserting or updating the value for <key> with <val>

.mergeAsync(sources, [options])

Merges the values in <sources> into the object currently encoded in the file.

.deleteKeyAsync(key, [options])

Deletes a single key from the top level of the file.

Functions

The functions available all mirror the methods above but take file (filename as a string) as their first argument.