Wasm-bindgen: Troubles with random numbers in WASM

[gabrielcarneiro97]

I'm trying to generate random numbers with this function:

    pub fn set_random(&mut self) {

        let max_max;

        if self.true_size.x * self.true_size.y / 2 > 10000 {
            max_max = 10000;
        } else {
            max_max = self.true_size.x * self.true_size.y / 2;
        }

        let max_range = Range::new(0, max_max);
        let mut rng = rand::thread_rng();
        let max = max_range.ind_sample(&mut rng) as i32;

        let mut coords : Vec<i32> = Vec::new();

        for _ in 0..max {
            let range_x = Range::new(0usize, self.true_size.x as usize);
            let range_y = Range::new(0usize, self.true_size.y as usize);

            let x = range_x.ind_sample(&mut rng) as i32;
            let y = range_y.ind_sample(&mut rng) as i32;

            coords.push(self.get_pos(&Coords {x, y}));
        }

        self.set_alive(coords);
    }

When I use it on Rust only, it works fine, but in WASM it throws this error:

There are any way to generate a random number in WASM?

[alexcrichton]

Thanks for the report! Unfortunately the rand crate doesn't work natively on wasm because its OsRng doesn't have an implementation. In the meantime though I've just published a crate, wbg-rand, which should allow you to use the rand crate on wasm32-unknown-unknown!

[gabrielcarneiro97]

You’re amazing buddy, thanks!