What is the difference between res.end() and res.send()?

Question

I'm a beginner in Express.js and I'm confused by these two keywords: res.end() and res.send().

Are they the same or different?

Answer 1

First of all, res.send() and res.end() are not the same.

I would like to make a little bit more emphasis on some key differences between res.end() & res.send() with respect to response headers and why they are important.

1. res.send() will check the structure of your output and set header information accordingly.

---

    app.get('/',(req,res)=>{
       res.send('<b>hello</b>');
    });

---

     app.get('/',(req,res)=>{
         res.send({msg:'hello'});
     });

Where with res.end() you can only respond with text and it will not set "Content-Type"

      app.get('/',(req,res)=>{
           res.end('<b>hello</b>');
      }); 

2. res.send() will set "ETag" attribute in the response header

      app.get('/',(req,res)=>{
            res.send('<b>hello</b>');
      });

¿Why is this tag important?
The ETag HTTP response header is an identifier for a specific version of a resource. It allows caches to be more efficient, and saves bandwidth, as a web server does not need to send a full response if the content has not changed.

res.end() will NOT set this header attribute