Always Parse JSON as Array

Question

How do I make sure that the json variable is always an array? In my code, sometimes str is an array and sometimes it isn't. Is there a way to make sure that it's always an array?

// array
const str = '[{ "key": "value" }]';
const json = JSON.parse(str);
console.log(json);
// [{
//   key: 'value'
// }]

// json
const str = '{ "key": "value" }';
const json = JSON.parse(str);
console.log(json);

// {
//   key: 'value'
// }

// What I want to happen somehow
const str = '{ "key": "value" }';
const json = JSON.parse(str);
console.log(json);

// [{
//   key: 'value'
// }]

I could check the type of json using instanceof, but I was hoping there would be a fancy ES6 way (with spread?) happen without it giving me an array of arrays with str is wrapped in brackets.

Tyler Roper · Accepted Answer · 2019-08-21 18:12:21Z

3

You could use concat which will either merge or wrap the parsed JSON.

const jsonObject = '{ "key": "value" }';
const result1 = [].concat(JSON.parse(jsonObject));
console.log(result1);

const jsonArray = '[{ "key": "value" }]';
const result2 = [].concat(JSON.parse(jsonArray));
console.log(result2);

edited Aug 21, 2019 at 18:12

answered Aug 21, 2019 at 17:59

Tyler Roper

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WilliamNHarvey · Accepted Answer · 2019-08-21 18:04:43Z

2

Make into an array then flatmap it, if the original json was an array the internal array will get removed.

const str1 = '[{ "key": "value" }]';
const json1 = [JSON.parse(str1)].flatMap(x => x);
console.log(json1);

const str2 = '{ "key": "value" }';
const json2 = [JSON.parse(str2)].flatMap(x => x);
console.log(json2);

answered Aug 21, 2019 at 18:04

WilliamNHarvey

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