generate a random string in rust wasm

wasm_random_string.rs

use rand_chacha::{self, rand_core::SeedableRng, rand_core::RngCore};
use web_sys;


let mut seed = [0u8; 8];
web_sys::window().unwrap().crypto().unwrap().get_random_values_with_u8_array(&mut seed).unwrap();
let mut s = 0u64;
for i in seed {
    s |= i as u64;
    s = s<<8;
}
const CHARSET: &[u8] = b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789)(*&^%$#@!~";
let mut rng = rand_chacha::ChaCha20Rng::seed_from_u64(s);
let cnonce: String = (0..64).map(|_| {
    let idx = rng.next_u32() as usize % CHARSET.len();
    CHARSET[idx] as char
}).collect();