Does scriptable support positive lookbehind assertions?

Scriptable
1

Can’t get my code to work. I’ve tried everything I can think of. I’ve double checked my syntax. Heck probably checked 10 times!


var url_video = 'https://www.instagram.com/tv/B7hj-tUhNkt/?igshid=m04ih801dy9n'
var url_pic = 'https://www.instagram.com/p/B7jYI8oll8w/?igshid=11vpf4r072mvh'


let r = new Request(url_pic)
let body = await r.loadString()

Pasteboard.copy(body)

var re = new RegExp("(?<=(<meta property=\"og:image\" content=\"))(.*)(?=\")")

var test = re.test(body)
var match = body.match(re)

// let webview = new WebView()

// await webview.loadURL(url_pic)



console.log(match[0])

Error message


2020-03-01 16:13:54: Error on line 10:20: SyntaxError: Invalid regular expression: invalid group specifier name
1 Like
2

That’s really a question about Apple’s javascript engine. I don’t believe Scriptable has its own engine.

3

I wonder if the issue is the double quotes outside the expression. Does it work if you just do something like this?:

var re = /(?<=(<meta property=\"og:image\" content=\"))(.*)(?=\")/i;
4

I get the same issue. Seems it’s an issue with the javascript engine as mentioned by @Martin_Packer. I figured as much but it’s annoying when some regex will work on some engines and not on others because I can’t tell how to know before hand if it will work or not.

5

You could always just use capture groups to get the same effect.

6

You can see which things are supported by which browsers here:

Scroll most of the way down and you’ll see that Safari (and ie and firefox) do not support look-behind assertions.

7

Ended up just doing a string slice with counting the start of the piece of the link i want up to the length of the string. I knew this would work as I have done this before. Thanks for the help.