How can I extract the number/id from the exponent token?

How to / Third Party Tooling
1

I am retrieving a push token using expo push notifications that looks like this

ExponentPushToken[rPCD4qJ_yJr0fkxoELSEk3]

I’d like to access only the number itself rPCD4qJ_yJr0fkxoELSEk3 so I can use it as a temporal user ID before the user signs up, but I’m not sure if this is possible to do.

Any solutions out there to do this that I’m missing?

2

I’ll leave it to you to google the exact syntax, but you should be able to use a JavaScript regular expression to get everything between the two brackets.

1 Like
3

Any hint on how to google this? I can’t find anything

4

https://www.google.com/search?client=firefox-b-1-d&sxsrf=ACYBGNSlcPh5ZDFp9ADhaFXLj81RAW9o-A:1580912359486&q=javascript+regex+expression+get+text+between+brackets&spell=1&sa=X&ved=2ahUKEwjxtu68zbrnAhUHXK0KHZ-YBj4QBSgAegQIDBAn&biw=1548&bih=928

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5

MDN is pretty good for stuff like this.

I found these by searching for “MDN regular expression”:

Based on the info above (and some regular expression knowledge), you could do something like this:

let pattern = /\[(.*)\]/;
let token = "ExponentPushToken[rPCD4qJ_yJr0fkxoELSEk3]";
let matches = pattern.exec(token);
if (matches) {
  console.log(matches[1]);
} else {
  console.log("Invalid token?");
}

You could also do this with String.prototype.indexOf() and String.prototype.slice():

let start = token.indexOf("[");
let end = token.indexOf("]");
if (start >= 0 && end > start) {
  console.log(token.slice(start + 1, end));
} else {
  console.log("Invalid token?");
}

Both of the snippets above assume the token is in the correct format. If some random string is used instead they might return nonsense or might log “Invalid token?”.

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