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JavaScript Express Basics Middleware Error Handling Middleware

Shehan Dissanayake
Shehan Dissanayake
19,119 Points
Posted by Shehan Dissanayake
Shehan Dissanayake
19,119 Points

res.locals

What actually res.locals do?

I found this is the docs

+An object that contains response local variables scoped to the request, and therefore available only to the view(s) rendered during that request / response cycle (if any). Otherwise, this property is identical to app.locals.

but im unable to understand it. Can someone explain? Please. Thanks

1 Answer

Boon Kiat Seah
Boon Kiat Seah
66,664 Points
Boon Kiat Seah
Boon Kiat Seah
66,664 Points

Hi Shehan,

You are passing the error object into the pug template to be rendered on the error.pug template file in this case. The code block below was used by Andrew. 

app.use((err, req, res, next) => {
    res.locals.error = err;
    res.status(err.status);
    res.render('error');
});

Another way Andrew taught which i am more familiar with is this code block below. However, both shared the same purpose of passing the object as a js object to be rendered by the pug template to display on the frontend. 

app.use((err, req, res, next) => {
    res.status(err.status);
    res.render('error', { error: err });
});

Check this url for more info on how variables are passed into the template if the above is still isn't clear for you.

Hope this helps. Have the best day ever.

regards,

BK