In javascript. The assignment is to finish a browser based game in which a truck

Question

In javascript. The assignment is to finish a browser based game in which a truck drives around catching falling kiwis, I'm having difficulty getting started with this funciton

Here are the requirements for process_frame()

This function is called by the game every single time the screen refreshes (60 times a second at best). It should do a few things:

if the user is pressing the "b" key, it should call brake_truck()

if the user is pressing the left arrow, it should call translate_truck_left()

if the user is pressing the right arrow, it should call translate_truck_right()

if the user is not pressing any of those keys, it should call coast_truck()

the function should call compute_truck_position() every time regardless of what key is pressed

the function should randomly decide whether to make a new kiwi start falling using the user's setting for the probability

Explanation / Answer

kiwi_caught = 0;

function process_frame() {
if (is_down('b')){
    brake_truck();
}
else if (is_down('left')) {
    translate_truck_left();
}
else if (is_down('right')) {
    translate_truck_right();
}
else {
    coast_truck();
}
compute_truck_position();
if (Math.random()*100 < kiwi_rate) {
      create_kiwi();
}
}

function translate_truck_right() {
    if (get_truck_velocity() < 20) {
         set_truck_velocity(get_truck_velocity() + 2.2);
     }
}

function translate_truck_left() {
if (get_truck_velocity() > -20) {
     set_truck_velocity(get_truck_velocity() - 2.2);
   }
}

function coast_truck() {
if (get_truck_velocity() != 0) {
    if (get_truck_velocity()>0) {
        set_truck_velocity(get_truck_velocity()*.96);
    }
    else if (get_truck_velocity()<0) {
        set_truck_velocity(get_truck_velocity()*.96);
    }
}
}

function brake_truck() {
   if (get_truck_velocity()>0){
    set_truck_velocity(get_truck_velocity()*.8);
}
else if (get_truck_velocity() < 0){
    set_truck_velocity(get_truck_velocity()*.8);
}
}

function compute_truck_position() {
newLeft = get_truck_left() + get_truck_velocity();
if (newLeft < 0) {
      set_truck_velocity(-.5*get_truck_velocity());
}
else if (newLeft > window.innerWidth-250) {
    set_truck_velocity(-.5*get_truck_velocity());
}
newLeft = get_truck_left() + get_truck_velocity();
   set_truck_left(newLeft);
}

// MUST BE IN BED OF TRUCK
function find_collisions(kiwi) {
if (get_kiwi_y(kiwi)>window.innerHeight-5){
    if(get_kiwi_x(kiwi)>get_truck_left()){
      if(get_kiwi_x(kiwi)<get_truck_left()+112){
              delete_kiwi(kiwi);
              document.getElementById("kiwi-count").innerHTML = ++kiwi_caught
      }
    }
}
}

function game_over() {
    alert("Congrats!","You caught " + kiwi_caught + " kiwi! Press the button again to start a new game!","New Game");
    document.getElementById("kiwi-count").innerHTML = 0;
    kiwi_caught = 0;
}

// just ignore this (but don't delete it):
check_latest = 2;

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