javascript - ES6 modules implementation, how to load a json file

Question

I'm implementing an example from https://github.com/moroshko/react-autosuggest

Important code is like this:

import React, { Component } from 'react';
import suburbs from 'json!../suburbs.json';

function getSuggestions(input, callback) {
  const suggestions = suburbs
    .filter(suburbObj => suburbMatchRegex.test(suburbObj.suburb))
    .sort((suburbObj1, suburbObj2) =>
      suburbObj1.suburb.toLowerCase().indexOf(lowercasedInput) -
      suburbObj2.suburb.toLowerCase().indexOf(lowercasedInput)
    )
    .slice(0, 7)
    .map(suburbObj => suburbObj.suburb);

  // 'suggestions' will be an array of strings, e.g.:
  //   ['Mentone', 'Mill Park', 'Mordialloc']

  setTimeout(() => callback(null, suggestions), 300);
}

This copy-paste code from the example (that works), has an error in my project:

Error: Cannot resolve module 'json' in /home/juanda/redux-pruebas/components

If I take out the prefix json!:

import suburbs from '../suburbs.json';

This way I got not errors at compile time (import is done). However I got errors when I execute it:

Uncaught TypeError: _jsonfilesSuburbsJson2.default.filter is not a function

If I debug it I can see suburbs is an objectc, not an array so filter function is not defined.

However in the example is commented suggestions is an array. If I rewrite suggestions like this, everything works:

  const suggestions = suburbs
  var suggestions = [ {
    'suburb': 'Abbeyard',
    'postcode': '3737'
  }, {
    'suburb': 'Abbotsford',
    'postcode': '3067'
  }, {
    'suburb': 'Aberfeldie',
    'postcode': '3040'
  } ].filter(suburbObj => suburbMatchRegex.test(suburbObj.suburb))

So... what json! prefix is doing in the import?

Why can't I put it in my code? Some babel configuration?

Answer 1

First of all you need to install json-loader:

npm i json-loader --save-dev

Then, there are two ways how you can use it:

1. In order to avoid adding json-loader in each import you can add to webpack.config this line:

   loaders: [
     { test: /.json$/, loader: 'json-loader' },
     // other loaders 
   ]
   

   Then import json files like this

   import suburbs from '../suburbs.json';
   

2. Use json-loader directly in your import, as in your example:

   import suburbs from 'json!../suburbs.json';
   

Note: In webpack 2.* instead of keyword loaders need to use rules.,

also webpack 2.* uses json-loader by default

*.json files are now supported without the json-loader. You may still use it. It's not a breaking change.

v2.1.0-beta.28