Question

I’d like to add acceleration in javascript. For instance, if I press and hold a button, then the object moves accelerated in the chosen direction.

Could someone suggest please, how to start this one? Should I log the time of the keypress? If yes, how can I do this?

Thank you

Answer 1

You should do dome research on Kinematics.

You can do this with a simple loop that models the correspondence between position, velocity and acceleration.

I’ve made a simple example (using jQuery for accessing DOM/CSS):

var position = 0;
var velocity = 0;
var acceleration = 0.1;

var $thing = $("#thing");

var loop = function () {
    $thing.css("left", position + "px");

    position = position + velocity;
    velocity = velocity + acceleration;
}

window.setInterval(loop, 100);

You can run it here: http://jsfiddle.net/QAn3Z/

Now you just need to add keypress detection.

This should get you started. Come back with more specific questions or problems, they will be less downvoted than “how should I begin” 😉