CodeHS Click for collision.

Click for collision.js

var RADIUS = 25;
var DX_RED = 6;
var DX_BLUE = 4;
var DELAY = 40;

var blueBall;
var redBall;
var colided = false;
var stopped = true;

function start(){
    blueBall = drawBall(RADIUS, Color.blue, 50, getHeight() / 2);
    redBall = drawBall(RADIUS, Color.red, getWidth() / 2, getHeight() / 2);
    
    mouseClickMethod(click);
}

function drawBall(radius, color, x, y){
    var ball = new Circle(radius);
    ball.setPosition(x, y);
    ball.setColor(color);
    add(ball);
    
    return ball;
}


function click(e){
    if ( stopped ) {
        setTimer(moveBalls, DELAY);
        stopped = false;
    } else {
        stopTimer(moveBalls);
        stopped = true;
    }
}

//moves blue ball
function moveBalls(){
    if (blueBall.getX() >= (redBall.getX() - RADIUS - RADIUS)) {
        colided = true;
    } 
    
    if (colided) {
        blueBall.move(DX_BLUE, 0);
        redBall.move(DX_RED, 0);
    }
    else {
        blueBall.move(DX_BLUE, 0);
    }
}

var blueCircle;
var redCircle;
var RADIUS = 25;
var DX_RED = 6;
var DX_BLUE = 4;
var DELAY = 40;
var clicks = 0;

function start(){
blueCircle = new Circle(RADIUS);
blueCircle.setPosition(50, getHeight()/2);
blueCircle.setColor(Color.blue);
add(blueCircle);

redCircle = new Circle(RADIUS);
redCircle.setPosition(getWidth()/2, getHeight()/2);
redCircle.setColor(Color.red);
add(redCircle);

mouseClickMethod(click);

}

function click(){
if(clicks%2==0){
setTimer(moveBall, DELAY);
clicks++;
}else{
stopTimer(moveBall);
clicks++;
}
}

function moveBall(){
if (blueCircle.getX() >= (getWidth()/2 - RADIUS*2)){
blueCircle.move(DX_BLUE, 0);
redCircle.move(DX_RED, 0);
}else{
blueCircle.move(DX_BLUE, 0);
}
}