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https://github.com/voltra/fetchjson

A Javascript library that allows to abstract all boilerplate from retrieving JSON data using the native ES6 fetch API
https://github.com/voltra/fetchjson

fetch-api fetchjson javascript-library promise

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A Javascript library that allows to abstract all boilerplate from retrieving JSON data using the native ES6 fetch API

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# fetchJSON #
A Javascript library that allows to abstract all boilerplate from retrieving JSON data using the native ES6 fetch API.

----------

Simple and easy to use, it only abstracts away all the boilerplate required for fetching json data.
No other javascript library is required to use this library.

----------
## Installation/Use ##
Just like every library should, I tried to make fetchJSON compatible with quite everything I am aware of.

fetchJSON currently supports regular use (via HTML script tag), npm and require (and commonJS), AMD (and probably ES6 modules ?).

Therefore, here are two ways to install this library:
***Without NPM***
```html







```

***With NPM***
```
npm install fetch_json
```
```javascript
const fetchJSON = require("fetch_json");
```

***With NPM and Babel***

`npm install fetch_json`

`import fetchJSON from "fetch_json"`

## Simple use case ##

Sometimes, you just have that json file which's sole purpose is configuration.
With fetchJSON, getting the data from this file is very easy:

```javascript
//With fetchJSON
let config_data;
fetchJSON("../../someFolder/someFile.json").then(data=>config_data=data);

//Without fetchJSON
let config_data;
fetch("../../someFolder/someFile.json").then(response=>{
/*gather headers*/
if(/*there's json in there*/)
return response.json().then(data=>{
/*some manipulation*/
config_data = data;
//finally !
});
else
/*handle error*/
});

```

Once loaded, the data can be used like this:
```javascript
fetchJSON("../../someFolder/someFile.json").then(config_data=>{
/* use data to configure your application*/
});
```

## Error Handling ##
One of the most important part of retrieving data asynchronously is error handling.
Sometimes you have server issues, sometimes you used an incorrect path and this can be a pain in the ass with regular fetch.

Version 1.0.5 (NPM, it's 1.05 on github) brings a whole new layer of abstracted boilerplate for error handling. Here's a simple example with, and without, fetchJSON.

```javascript
//with fetchJSON
fetchJSON("../../someFolder/someFile.json")
.then(/*some manipulations*/)
.then(/*some manipulations*/)
.catch(errorMsg=>{
/*handle errors here*/
});

//without fetchJSON
new Promise((resolve, reject)=>{
fetch("../../someFolder/someFile.json").then(response=>{
/*gather headers*/
if(/*there's json in there*/)
return response.json().then(data=>{
/*some manipulation*/
//finally !
resolve(data);//important
});
else
reject(/*handle error*/)
});
})
.then(/*some manipulations*/)
.then(/*some manipulations*/)
.catch(errorMsg=>{
/*handle errors here*/
});
```
From version 1.0.5, fetchJSON is completely thenable and catchable just like any other good Promise-based library \o/ !

## Motivations ##
As you can see, fetchJSON really focuses on what's important : using the data. Whereas the regular fetch approach is mostly boilerplate and takes up a lot of space in your code, and most of that space is here solely to get the data not using it.

JSON is a precious resource, it would be a shame to spend more time on getting its data than using it.

## Questions/Suggestions ##
Please fill free to ask for help or post suggestions on my github repository, I'll be more than glad to take care of your problems/concerns.

#Hot updates

### A bit more Promise style

Since v1.10 you can use full Promise style to fetch your data :

```javascript
let data = null;
fetchJSON("/path/to/file/dot.json")
.then(json => data=json);

//Is strictly equivalent to

let data = null;
fetchJSON("/path/to/file/dot.json", json => data=json);
```

## Complete 180°

Since v2.0.0 the second argument, which was a callback function (same behavior as a simple `then`), has been changed to an object of data :

This object of data must be:

* Not provided (defaulted to `{}`)
* an empty object
* an object of numbers and/or strings
* an object of numbers and/or strings and/or arrays (that only contains numbers and/or strings)

This allows you to construct the query string easily :

```javascript
fetchJSON("/api/user", {
id: 42,
item: "player_profile"
props: [
"rank",
"ratio"
]
}); //Will conduct a GET request to /api/user?id=42&item=player_profile&props=rank&props=ratio

///OR

fetchJSON("/api/user?", {
id: 42,
item: "player_profile"
props: [
"rank",
"ratio"
]
}); //Will conduct a GET request to /api/user?id=42&item=player_profile&props=rank&props=ratio

///OR

fetchJSON("/api/user?test=1", {
id: 42,
item: "player_profile"
props: [
"rank",
"ratio"
]
}); //Will conduct a GET request to /api/user?test=1&id=42&item=player_profile&props=rank&props=ratio

///OR

fetchJSON("/api/user?test=1&", {
id: 42,
item: "player_profile"
props: [
"rank",
"ratio"
]
}); //Will conduct a GET request to /api/user?test=1&id=42&item=player_profile&props=rank&props=ratio
```

## Changes
### v2.2.0
In an effort to make the library as usable as possible, I refactored the options/query string/headers merging algorithm to use deep merging instead of shallow merging.

### v2.1.0

In an effort to provide more customization, `fetchJSON` now exposes a third argument : `options`. This is an object following the same interface as `fetch`'s `init` [argument](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Parameters), with the only enforcement being that headers come as an object and not an object or an array.

It also exposes `fetchJSON.defaults` with three properties : `qs`, `options` and `headers` :

* `qs` is merged w/ the `data` argument of `fetchJSON`
* `headers` is merged w/ the `headers` property of the `options` argument of `fetchJSON`
* `options` is merged w/ the `options` argument of `fetchJSON`