在node.js中区别beetwen path.join（__ dirname，'views'）和path.join（__ dirname +'views'）

Question

im stuck with node.js again.

i try the first path.join in my code for setup view engine its not working, the index won't showing up, then i change to path.join(__dirname , 'views'); and its working well, the index showing, i dont know how

can someone explain how this work ?

path.join(__dirname + 'views');

path.join(__dirname, 'views');

this is my script

app.set('views', path.join(__dirname, 'views')); //its work
app.set('views', path.join(__dirname + 'views')); // if i change like this, its not work

Answer 1

path.join constructs a path from your arguments by concatenating them with "/". So path.join(__dirname, 'views') results in /path_to_dir/views

On the other hand, (__dirname + 'views') only has one parameter (__dirname+views). This means there are no additional arguments to join to the first and so you end up with "/path_to_dirviews" (No joining "/")

Answer 2

The default function uses commas as separator, not plus sign, that's why it works with comma and not with plus.

See documentation for path.join() in node.js

Answer 3

From Official documentation: https://nodejs.org/api/path.html#path_path_join_paths

Paths that u join must be separated by a delimiter;

Also if all paths are not strings, then an error will be thrown.

So, I presume the addition of + makes path go crazy because, it cannot find a delimiter and also it finds that the paths that u have mentioned are not all strings.

Hope this helps.

Answer 4

for know the difference on this function, you have the official node.JS documentation

The first method using the Javascript concatenation have a different result that using a method parameters:

Using standard javascript :

let folder = '/folder';
let subFolder = 'sub';

path.join(folder + sub ) // result : /foldersub

But, with properly use the paramters of this method, the path is different: This method format all parameters for create a standard part with /

let folder = '/folder';
let subFolder = 'sub';

path.join(folder, sub) // result : /folder/sub

Don't forget you cano use the console.log(path) for debug in Javascript... link for using it here

Answer 5

path.join is a function. Using the + operator means you send only one argument which is a concatenation of __dirname and 'views'. The function should return a path which is constructed from the arguments passed. In you case just one, so it won't be a valid path.