如何在express.js中获取请求查询参数的数量？

Question

At the moment I have to check every potentially existing parameter separately.

if (req.query.param1 != undefined ) {
}
if (req.query.param2 != undefined ) {
}
if (req.query.param3 != undefined ) {
}
...

Answer 1

To get all query parameter:

Object.keys(req.query)

To get number of all params:

Object.keys(req.query).length

Then you can iterate through all parameters:

for(p in req.query) {
  //... do something
}

UPD:

surround your request with quotes to make right query

curl -X GET "localhost:9090/mypath?param1=123&param2=321"

without quotes the & in terminal makes the command run in the background.

Answer 2

If you hit /mypath?param1=5&param2=10 , then the request.query will yield {param1: 5, param2:10} .

This means that the request.query is a JavaScript object with the key as the name of the param, and value as the value of the param. Now you can do anything with it as you want: Find the length or iterate over it as follows:

for (var key in request.query) {
  if (request.query.hasOwnProperty(key)) {
    alert(key + " -> " + request.query[key]);
  }
}

Finding only the length might not work for you that well because you may have param1 and param3 , with param2 missing. Iterating will be better IMO.

Answer 3

You want the number of non-undefined params right? It is as simple as this;

var no = 0;
for (var key in req.query) { 
    if(req.query[key]) no++;
}