Mirror of forum.nim-lang.org

8272 :: String formatting a number with Javascript backend

• KerryC (orginal) [2021-07-27T07:29:30+02:00] view original

  I've encountered an error when trying to use strformat with a number in the Javascript backend. It's not a show stopper as there is another way. But it is really bugging me that I don't understand why I am encountering a problem and I would prefer to use the strformat approach.

  If I have this:

  import strformat, jsffi
  var
      obj = JsObject{field: 1}
      s = obj.field.to(cstring)
  Run

  Why does this work?

  var f1 = s & " is a string".cstring
    console.log(f1)
  Run

  But this doesn't:

  var f2 = fmt"{s} is a string".cstring
    console.log(f2)
  Run

  I get this error in the console: "Uncaught RangeError: Invalid array length"

  I would appreciate it if someone could explain this to me!

---

• juancarlospaco (orginal) [2021-07-27T07:41:52+02:00] view original

  Use string instead of cstring, strformat can take string, only use cstring on the outer borders and if you really need it.

---

• KerryC (orginal) [2021-07-27T08:22:19+02:00] view original

  Thank you for your reply!

  I'm still confused though.

  I can do this and strformat seems to have no issue with cstring

  import jsffi, strformat, jsconsole
  
  var
    obj = JsObject{field: "1".cstring}
    s = obj.field.to(cstring)
  
  var f = fmt"{s} is a string".cstring
  console.log(f)
  Run

  If I try to convert to a string:

  var
    obj = JsObject{field: 1}
    s = obj.field.to(string)
  
  var f = fmt"{s} is a string".cstring
  console.log(f)
  Run

  I get this error: Uncaught TypeError: src_33557137.slice is not a function

---