json token decode code example

Example 1: javascript token generator

function generate_token(length){
    //edit the token allowed characters
    var a = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890".split("");
    var b = [];  
    for (var i=0; i<length; i++) {
        var j = (Math.random() * (a.length-1)).toFixed(0);
        b[i] = a[j];
    }
    return b.join("");
}
generate_token(32); //returns "qweQj4giRJSdMNzB8g1XIa6t3YtRIHPH"

Example 2: decode jwt tokens

let b64DecodeUnicode = str =>
  decodeURIComponent(
    Array.prototype.map.call(atob(str), c =>
      '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2)
    ).join(''))

let parseJwt = token =>
  JSON.parse(
    b64DecodeUnicode(
      token.split('.')[1].replace('-', '+').replace('_', '/')
    )
  )

Example 3: jwt

JSON Web Token is an Internet standard for creating data with optional
signature and/or optional encryption whose payload holds JSON that asserts
some number of claims.

The tokens are signed either using a private secret or a public/private key.