replace functionality broken in 4 and 4.1

[bodyslam]

Hello

There seems to be an issue with Node's implementation of replace. The behavior appears to escape the backslashes; please see the output below:

> dev twong$  node -v
v4.0.0
nyl7twong:dev twong$ node
> a = "\\a\\b";
'\\a\\b'
> a.replace(/\\\\/g, '\*')
'\\a\\b'
> a.replace(/\\/g, '\*')
'*a*b'
> a.replace(/\\/g, '\\')
'\\a\\b'

Now using node v4.1.2
nyl7twong:dev twong$ node -v
v4.1.2
nyl7twong:dev twong$ node
> a = "\\a\\b";
'\\a\\b'
> a.replace(/\\\\/g, '\*')
'\\a\\b'
> a.replace(/\\/g, '\*')
'*a*b'
> a.replace(/\\/g, '\\')
'\\a\\b'

Chrome's output (via console)

a = "\\a\\b"
"\a\b"
a
"\a\b"
a = "\\\\a\\\\b"
"\\a\\b"
a.replace(/\\\\/g, '\\');
"\a\b"

[bnoordhuis]

I'm not sure what you're getting at. Are you confused by the REPL printing backslashes in escaped form?

[bodyslam]

My apologies I pasted a missing example which is core to the issue:

> nyl7twong:dispatcher twong$ node -v
v4.1.2
nyl7twong:dispatcher twong$ node
> a = '\\a\\b'
'\\a\\b'
> a.replace(/\\\\/, '\\')
'\\a\\b'
> 

The core issue here is the replace function; given the string
a = '\\a\\b';
I'd like to replace the double backslash with a single backslash using
a.replace(/\\\\/g, '\\')

Which gives me "\\a\\b" (see the examples above) in Node 4 and 4.1
The Chrome example above gives the expected output of "\a\b" using the same method

[bnoordhuis]

There are no double backslashes in a = '\\a\\b', they are parsed to single slashes. You can check that yourself with console.log(a), it prints \a\b.

[Trott]

While there is no issue with .replace() functionality here, there is a confusing difference between the Node.js REPL and the console in Chrome.

Node.js REPL:

> a = "\\a\\b";
'\\a\\b'
> 

Chrome console:

> a = "\\a\\b";
"\a\b"
>

Not saying anything needs to be done necessarily, but worth noting at least, I think.

[Fishrock123]

Node.js REPL:

I suspect the repl is not formatting strings. Could that be the case?

[silverwind]

Firefox too turns a '\\' into '\' for console output, so the browser consensus seems to be to print backslashes unescaped in string literals. The downside to this is that one needs to escape them again when copy-pasting from repl into code.

[bricss]

Seems not an issue at all.

[bnoordhuis]

Agreed, closing.

[noscripter]

find the repl ouput confusing too.

[targos]

I personally think browser's output is more confusing:

[lili21]

If you don't think it's a issue, How can I save a value like a\/b ?

I need to create a json file contain the regexp string stuff.

{
  "regex": "a\/b"
}

[bricss]

Here you go:

var str = String.raw`a\/b`;

[lili21]

Thanks, didn't know that function before.

But I need to write the content fo a file and use JSON.stringify function. and That would make it become a\\/b.

[bricss]

That's right. Then you can do new RegExp('a\\/b') to use it as regular expression from parsed JSON.

[lili21]

Thank you @bricss . really helpful.

[sivam93]

hi ,
Can you help me out with the same problem.
Console.log prints single slach(]) in REPL for the below code

var user="DOMAIN\USERNAME"

console output:DOMAIN\USERNAME.

I am Trying to the user to connect to mssqlserver data base using mssql package.

After assigning the user, and when tried to print the config getting the below output
Code:
var config = {
server: 'DEV',
user: 'DOMAIN\USERNAME',
password: 'XXXX',
database: 'TEMP'
}

NODE REPL OUTPUT:
{ server: 'DEV',
user: 'DOMAIN\USERNAME',
password: 'XXX',
database: 'TEMP' }

Seems to be the same issue but because of this not able to connect to the db, getting error: ConnectionError: Login failed for user