Express: how the app.set('view engine','ejs') executed innerly? - node.js

Question

So I know the method app.set() is that setting value for a name. therefore, app.get() could get the value by name. but accordingly, if I set 'view engine' to 'ejs',where is the app.get('view engine')? if not have, how dose the app.set('view engine','ejs') work?
thank you for responding this wizard question.

Answer 1

It works as You expect:
How it works?
Check this: https://github.com/expressjs/express/blob/master/lib/application.js#L336
From line: 336
/**
* Assign `setting` to `val`, or return `setting`'s value.
*
* app.set('foo', 'bar');
* app.get('foo');
* // => "bar"
*
* Mounted servers inherit their parent server's settings.
*
* #param {String} setting
* #param {*} [val]
* #return {Server} for chaining
* #public
*/
app.set = function set(setting, val) {
if (arguments.length === 1) {
// app.get(setting)
return this.settings[setting];
}
debug('set "%s" to %o', setting, val);
// set value
this.settings[setting] = val;
// trigger matched settings
switch (setting) {
case 'etag':
this.set('etag fn', compileETag(val));
break;
case 'query parser':
this.set('query parser fn', compileQueryParser(val));
break;
case 'trust proxy':
this.set('trust proxy fn', compileTrust(val));
// trust proxy inherit back-compat
Object.defineProperty(this.settings, trustProxyDefaultSymbol, {
configurable: true,
value: false
});
break;
}
return this;
};