How do I check if query string has values in Express.js/Node.js?

Question

How do I check if a query string passed to an Express.js application contains any values? If I have an API URL that could be either: http://example.com/api/objects or http://example.com/api/objects?name=itemName, what conditional statements work to determine which I am dealing with?

My current code is below, and it always evaluates to the 'should have no string' option.

if (req.query !== {}) {
    console.log('should have no query string');
}
else {
    console.log('should have query string');
}

Not sure of `node`'s support of this, but maybe you could use [this answer](http://stackoverflow.com/a/5533226/2708970) to check if the length of `req.query` is greater than 0. — Brendan, Oct 10 '14 at 05:08

Ravi · Accepted Answer · 2014-10-10T05:30:35.593

44

All you need to do is check the length of keys in your Object, like this,

Object.keys(req.query).length === 0

Sidenote: You are implying the if-else in wrong way,

if (req.query !== {})     // this will run when your req.query is 'NOT EMPTY', i.e it has some query string.

edited Oct 10 '14 at 05:30

answered Oct 10 '14 at 05:19

Ravi

1,320
12
19

Thanks! Yeah, that mistake was a typo in converting my real code for the question. – blundin Oct 10 '14 at 12:54

Pranav Shekhar Jha · Answer 2 · 2014-10-10T05:27:02.333

8

If you want to check if there is no query string, you can do a regex search,

if (!/\?.+/.test(req.url) {
    console.log('should have no query string');
}
else {
    console.log('should have query string');
}

If you are looking for a single param try this

if (!req.query.name) {
    console.log('should have no query string');
}
else {
    console.log('should have query string');
}

edited Oct 10 '14 at 05:27

answered Oct 10 '14 at 05:18

Pranav Shekhar Jha

191
4

score 1 · Answer 3 · answered Oct 03 '19 at 06:56

1

We can use underscore JS Library

Which has built in function isEmpty(obj). This returns true/false.

So, the code will look like :-

const underscore = require('underscore');
console.log(underscore.isEmpty(req.query));

answered Oct 03 '19 at 06:56

Nikhil Vats

291
3
7

Dude, underscore is long gone. Use lodash. – atilkan Oct 03 '19 at 13:16

score 1 · Answer 4 · answered Apr 28 '20 at 13:45

I usually check if the variable in the query string is defined. Using the url package in ExpressJS it would be so:

var aquery = require('url').parse(req.url,true).query;

if(aquery.variable1 != undefined){
  ...
  ....
  var capturedvariablevalue = aquery.variable1;
  ....
  ....

}
else{
  //logic for variable not defined
  ...
  ...
  //
}

How do I check if query string has values in Express.js/Node.js?

4 Answers4