In Node.Js Express, does “res.render” end the http

问题:

So, only do "res.render" when you are sure that everything has finished, right? Because it ends the request and shoots out a webpage.

回答1:

If you don't provide a callback to res.render(view[, options[, fn]]) it will automatically give a response with 200 HTTP Status and Content-Type: text/html

res.render('view', {}, function() {
    while (true); // should block 
});

res.render(view[, options[, fn]])

Render view with the given options and optional callback fn. When a callback function is given a response will not be made automatically, however otherwise a response of 200 and text/html is given.

express.js guide

回答2:

With the current github master commit, this is res.render in lib/view.js:

 /**
 * Render `view` with the given `options` and optional callback `fn`.
 * When a callback function is given a response will _not_ be made
 * automatically, however otherwise a response of _200_ and _text/html_ is given.
 *
 * Options:
 *  
 *  - `scope`     Template evaluation context (the value of `this`)
 *  - `debug`     Output debugging information
 *  - `status`    Response status code
 *
 * @param  {String} view
 * @param  {Object|Function} options or callback function
 * @param  {Function} fn
 * @api public
 */
res.render = function(view, opts, fn, parent, sub){
  // support callback function as second arg
  if ('function' == typeof opts) {
    fn = opts, opts = null;
  }

  try {
    return this._render(view, opts, fn, parent, sub);
  } catch (err) {
    // callback given
    if (fn) {
      fn(err);
    // unwind to root call to prevent
    // several next(err) calls
    } else if (sub) {
      throw err;
    // root template, next(err)
    } else {
      this.req.next(err);
    }
  }
};