fetch_json
v2.2.0
Published
A javasript library that makes it easy to retrieve JSON data from a JSON file
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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>
<!-- [...] -->
<head>
<!-- [...] -->
<script src="path/to/fetchJSON.js"></script>
<!-- [...] -->
</head>
<!-- [...] -->
</html>With NPM
npm install fetch_jsonconst 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:
//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:
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.
//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 :
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 :
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=ratioChanges
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, 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 :
qsis merged w/ thedataargument offetchJSONheadersis merged w/ theheadersproperty of theoptionsargument offetchJSONoptionsis merged w/ theoptionsargument offetchJSON