is there any way to validate if a string is a valid nanoid?

[lsuarezj]

I have an array of strings and want to ensure all strings are nanoids. I was thinking about using regex, maybe there's other way.

[ai]

Regexp is the only way

[lsuarezj]

thanks for your reply! 👍

[Garibaldi2000]

@ai

[Ephellon]

Adding examples and explanations for future reference, and newcomers.

As @ai answered, RegExp is the easiest way:

function verifyID(id) {
    // Returns false if any character is not a word (A-Za-z0-9_) or dash (-)
    return !/[^\w\-]/.test(id);
}

If you know the alphabet used to make the ID, you can do the following:

function verifyID(id) {
    // We're expecting a string...
    if(!(typeof id == 'string') || !(id instanceof String))
        throw new Error("verifyID should be called as: `verifyID(id:string) → boolean`");

    // We want to know what characters are being used...
    let legalCharacters = (nanoid.alphabet || "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-");

    // Not required. Just removes duplicate characters.
    let usedCharacters = new Set(id);

    // If there is an unknown character in the id, return false
    for(let character of usedCharacters)
        if(!(legalCharacters.includes(character)))
            return false;
    return true;
}

[SudoerWithAnOpinion]

Since Google dropped me here, I might as well drop a faster, more robust function (for typescript specifically):

type NanoID = Branded<string, "NanoID">; // Implement your own Branding type

const NANOID_LENGTH = 8; // from nanoid-dictionary
const NANOID_ALPHABET = nolookalikes; 

const isNanoId = (id: unknown): id is NanoID => {
  if (typeof id !== 'string') return false;
  // Check if illegal chars exit
  const regex = new RegExp(`^[${NANOID_ALPHABET}]{${NANOID_LENGTH}}$`);
  return regex.test(id);
};