Convert string array values from URLSearchParams

Question

How does one convert string array values into a Javascript array object?

var querystring = 'lang[]=EN&lang[]=FR&type[]=1&type[]=2';

Into:

{
    lang: ['EN', 'FR'],
    type: ['2']
}

Below my attempt:

let params = new URLSearchParams(decodeURI(querystring));
let entries = params.entries();

let result = {}
for(let entry of entries) { // each 'entry' is a [key, value]
    result[entry[0]] = entry[1];
}
return result;

Which results in:

[{
    "name": "lang[]",
    "value": "EN"
}, {
    "name": "lang[]",
    "value": "FR"
}, {
    "name": "type[]",
    "value": "2"
}]

don't understand the expected output, type: [1,2] would make a little sense. — xianshenglu
– xianshenglu, Commented Dec 20, 2018 at 2:08
Why not use something like npmjs.com/package/query-string or npmjs.com/package/qs — Bergur
– Bergur, Commented Dec 20, 2018 at 2:15

Bergur · Accepted Answer · 2018-12-20 02:22:47Z

3

Simplest version would be to use a library like qs

https://www.npmjs.com/package/qs#parsing-arrays

var withArray = qs.parse('a[]=b&a[]=c');

ressults in

a: ['b', 'c']

answered Dec 20, 2018 at 2:22

Bergur

4,07714 silver badges21 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

bart Over a year ago

I am not running Node.js

Bergur Over a year ago

You don't have to. Its just Javascript. There's even a CDN cdnjs.com/libraries/qs

Mark · Accepted Answer · 2018-12-20 02:43:03Z

3

You should probably test for the [] so your code won't break with entries not ending in []. You can then slice off the [] so your keys don't include it:

var querystring = 'lang[]=EN&lang[]=FR&type[]=1&type[]=2&test=hello';

let params = new URLSearchParams(decodeURI(querystring));
let entries = params.entries();

let result = {}
for(let entry of entries) { // each 'entry' is a [key, value]
    let [key, val] = entry
    if (key.endsWith('[]')){         // array 
      key = key.slice(0,-2);         // clean up the key
      (result[key] || (result[key] = [])).push(val)
    } else {
      result[key] = val             // normal parameter
    }
}
console.log(result)

edited Dec 20, 2018 at 2:43

answered Dec 20, 2018 at 2:31

Mark

92.6k8 gold badges116 silver badges156 bronze badges

Comments

yip102011 · Accepted Answer · 2018-12-20 02:19:43Z

2

var querystring = 'lang[]=EN&lang[]=FR&type[]=1&type[]=2';
let params = new URLSearchParams(decodeURI(querystring));
let entries = params.entries();

let result = {}
for(let entry of entries) { // each 'entry' is a [key, value]
    var key = entry[0];
    var val = entry[1];
    if(key in result){
        result[key].push(val);
    }else{
        result[key] = [val];
    }
}
console.log(result);

answered Dec 20, 2018 at 2:19

yip102011

8975 silver badges12 bronze badges

2 Comments

João Belo Over a year ago

use var key = entry[0].replace("[]", ""); instead

halloei Over a year ago

Like @Mark said, this breaks query strings with parameters that are not an array.

Collectives™ on Stack Overflow

Convert string array values from URLSearchParams

3 Answers 3

2 Comments

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related