sketch.js

var symbolSize = 30;
var streams = [];
var backgroundColor = 0;
var canvasWidth = window.innerWidth;
var canvasHeight = window.innerHeight;

var minSymbolsSpeed = 6;
var maxSymbolsSpeed = 12;

var minStreamLenght = 5;
var maxStreamLenght = 30;

function setup(){
    createCanvas(
        canvasWidth,
        canvasHeight
    );
    background(backgroundColor);
    textSize(symbolSize);

    var x = 0; 
    for (var i = 0; i<= width / symbolSize; i++){
        var stream = new Stream();
        stream.generateSymbols(x, random(-1000,0));
        streams.push(stream);
        x+=symbolSize;
    }
}

function draw(){
    background(backgroundColor, 180);
    streams.forEach(function(stream){
        stream.render();
    });
}

function Symbol(x, y, speed, isFirst){
    this.x = x;
    this.y = y;
    this.speed = speed;
    this.switchInterval = round(random(2,20));
    this.isFirst = isFirst;
    
    this.value;

    this.setToRandomSymbol = function(){
        if(frameCount % this.switchInterval == 0){
            this.value  = String.fromCharCode(
                0x30A0 + round(random(0,96))
            );
        }
    }

    this.moveDown = function(){
        if(this.y >= height)
            this.y = 0;
        else
            this.y += this.speed;
    }
}


function  Stream(){
    this.symbols = [];
    this.totalSymbols = round(random(minStreamLenght, maxStreamLenght));
    this.speed = round(random(minSymbolsSpeed, maxSymbolsSpeed));

    this.generateSymbols = function(x, y){
        var first = round(random(0,4)) == 1;
        for(var i = 0; i<= this.totalSymbols; i++)
        {
            var symbol =  new Symbol(x, y, this.speed, first);
            symbol.setToRandomSymbol();
            this.symbols.push(symbol);
            
            y -= symbolSize;
            first = false;
        }
    }

    this.render = function (){
        this.symbols.forEach(function(symbol){
            if(symbol.isFirst)
                fill(180,255,180);
            else
                 fill(0,255,70)
            text(symbol.value, symbol.x, symbol.y);
            symbol.moveDown();
            symbol.setToRandomSymbol();
        })
    }
}