So I have a game, and Im trying to keep it from starting unless the user pressed the Enter key.
This is the code I have for that:
var code = (e.keyCode ? e.keyCode : e.which);
var enterpressed = 0;
do {
if(code == 13) { //Enter keycode
enterpressed = 13;
}
ctx.font = "25px Helvetica";
drawStartScreen();
update();
} while (enterpressed === 13);
This is the full program, on JSfiddle:
http://jsfiddle.net/3aoozxte/6/
Edit: I figured it out!
Here is the program working:
http://jsfiddle.net/84c2k5kg/6/
Here is the solution to your problem.
I added the enter key logic to your keydown eventlistener. So when you press enter it starts the game.
I deleted the loop in startGameScreen() to prevent the browser crashing repeating this infinite loop.
http://jsfiddle.net/3aoozxte/19/
function main() {
canvas = document.createElement("canvas");
canvas.width = COLS*20;
canvas.height = ROWS*20;
ctx = canvas.getContext("2d");
document.body.appendChild(canvas);
ctx.font = "12px Helvetica";
frames = 0;
keystate = {};
started = false;
// keeps track of the keyboard input
document.addEventListener("keydown", function(evt) {
keystate[evt.keyCode] = true;
if(keystate[Key_ENTER] && !started) { // Start the game if it's not started and Enter is pressed.
started = true;
init();
loop();
}
});
document.addEventListener("keyup", function(evt) {
delete keystate[evt.keyCode];
});
//Attempting to create a welcome screen
startGameScreen();
}
function startGameScreen() {
ctx.font = "25px Helvetica";
drawStartScreen();
}
This might be the one you are looking for.
document.onkeydown = function(evt) {
evt = evt || window.event;
if (evt.ctrlKey && evt.keyCode == 90) {
alert("Ctrl-Z was pressed");
}
else {
var kc = evt.keyCode
switch(kc){
case 13 : alert("Enter was pressed"); break
case 37 : alert("Left Key was pressed"); break
case 38 : alert("Up Key was pressed"); break
case 39 : alert("Right Key was pressed"); break
case 40 : alert("Down Key was pressed"); break
// default : alert(kc + " was pressed");//used to check for key value
}
}
};
Fiddle Key Events
Adding the function on your listener..
document.onkeydown = function(evt) {
if (evt.keyCode == 13) {
started = true;
init();
loop();
}
}
Updated and working Game
Complete reference Complete Handling Key Events
I prefer using jquery
$(document).keypress(function(e)
{
if (e.which == 13)
{
//Your code
}
});
Related
I have some issues: I have this : (in a function..)
var space = 0;
setInterval(space, 20);
var keys = {}
$(document).keydown(function(e) {
keys[e.keyCode] = true;
});
$(document).keyup(function(e) {
delete keys[e.keyCode];
});
function space() {
for (var direction in keys) {
if (!keys.hasOwnProperty(direction)) continue;
if (direction == 32) {
space++;
console.log(space);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
32 == Space key, but I saw in the console that space is pressed 3 times (space == 3), keyup keypress and keydown (I think), how can I have just "space = 1" when space is pressed ?
What seems to be happening is that since it's running every 20 ms, as you hold down the space bar the space function is continuously incrementing the count. I added a flag to prevent another execution until the key is released and it works fine. Really you should just use the keypress event and check there if the keyCode === 32 to track your count. Fewer events will be fired. If you want to see what was happening you can comment out the flag and check the console.
var spaceCount = 0;
var running = false;
var keys = {}
$(document).keydown(function(e) {
console.log("keycode", e.keyCode);
keys[e.keyCode] = true;
});
$(document).keyup(function(e) {
console.log("keyup")
delete keys[e.keyCode];
running = false;
});
function space() {
if(running) return;
for (var direction in keys) {
running = true;
console.log(direction);
if (!keys.hasOwnProperty(direction)) continue;
if (direction == 32) {
spaceCount++;
console.log("count: " + spaceCount);
console.log(keys);
}
}
}
setInterval(space, 20);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
I hope that will be helpful:
var space = 0;
var keys = {};
var keys2 = {};
$(document).keydown(function(e) {
keys[e.keyCode] = true;
});
$(document).keyup(function(e) {
keys[e.keyCode] = false;
});
setInterval(function(){spacing()}, 20);
function spacing() {
if (keys[32] && !keys2[32])
{
space++;
keys2[32] = true;
}
else if(!keys[32])
{
keys2[32] = false;
}
console.log(space);
}
I'm currently building a music player with three buttons (actually simple divs) for Play/Pause (id="play"), Previous (id=rew) and Next (id="fwd").
I want the Play/Pause to be "clicked" when pressing SPACEBAR.
I want the Previous to be "clicked" when pressing LEFT ARROW.
I want the Next to be "clicked" when pressing RIGHT ARROW.
I've successfully managed the SPACEBAR control of Play with this :
var play = document.getElementById("play");
document.onkeydown = function (e) {
if (e.keyCode == 32) {
play.click();
}
};
However, when I add the same for the two other buttons in my script, the SPACEBAR control of Play does not work anymore, as well as the other two.
So, what I have currently in my script and which is obviously not working is this :
<script>
var play = document.getElementById("play");
document.onkeydown = function (e) {
if (e.keyCode == 32) {
play.click();
}
};
var rew = document.getElementById("rew");
document.onkeydown = function (e) {
if (e.keyCode == 37) {
rew.click();
}
};
var fwd = document.getElementById("fwd");
document.onkeydown = function (e) {
if (e.keyCode == 39) {
fwd.click();
}
};
</script>
What am I doing wrong ?
Each of your keydown events is overwriting the previous one.
Instead, put all the logic into one keydown event, like this:
var play = document.getElementById("play");
var rew = document.getElementById("rew");
var fwd = document.getElementById("fwd");
document.onkeydown = function(e) {
if (e.keyCode == 32) {
play.click();
} else if (e.keyCode == 37) {
rew.click();
} else if (e.keyCode == 39) {
fwd.click();
}
};
When you assign to onkeydown several times only the last one will be assigned because it will override the previous one. You can use addEventListener instead but that isn't the best approach neither. Just make more test inside one event listener like this:
var play = document.getElementById("play");
var rew = document.getElementById("rew");
var fwd = document.getElementById("fwd");
document.onkeydown = function (e) {
if (e.keyCode == 32) {
play.click();
}
else if(e.keyCode == 32) {
rev.click();
}
else if(e.keyCode == 32) {
fwd.click();
}
};
in the code below i'm trying to get it to log "success" into the console when I press the "w" button, but for some reason it's not doing anything when I press it. can someone tell me what I'm doing wrong?
var keysDown = {};
var keysUp = {};
window.addEventListener('keydown', function(e) {
keysDown[e.keyCode] = true;
});
window.addEventListener('keyup', function(e) {
delete keysDown[e.keyCode];
keysUp[e.keyCode] = true;
});
if (37 in keysDown || 65 in keysDown) { //left
console.log("success");
}
window.addEventListener('keyup', function(e) {
console.log(e.keyCode)
if(e.keyCode == 37 || e.keyCode == 65) console.log('yay')
});
http://jsfiddle.net/zackify/anq34vsv/ Just check for the keycode in the event listener function.
I feel like a complete klutz, I had this working and then I accidentally forgot to save it! I'm an idiot. I've spent the last day trying to recreate what I had but I can't do it. Basically (from my last save) I had this:
function canvasMove(e) {
if(!e) var e = window.event;
var downcheck;
var upcheck;
var leftcheck;
var rightcheck;
if(e.keyCode == '38') {
if(up + down == 0) downcheck = false;
else downcheck = true;
e.preventDefault();
}
if(e.keyCode == '40') {
if(up + down > HEIGHT - 110) upcheck = false;
else upcheck = true;
e.preventDefault();
}
if(e.keyCode == '37') {
if(left + right == 0) rightcheck = false;
else rightcheck = true;
e.preventDefault();
}
if(e.keyCode == "39") {
if(left + right > WIDTH - 110) leftcheck = false;
else leftcheck = true;
e.preventDefault();
}
if(leftcheck == true) { left += 10; counting() };
if(rightcheck == true) { right -= 10; counting() };
if(upcheck == true) { up += 10; counting(true) };
if(downcheck == true) { down -= 10; counting(true) };
}
The problem of course being that Javascrpt doesn't support the ability to check if two keys are being pressed at the same time. What I want to accomplish is when the user pressed up and left they'll move diagonally. Ignore the "counting" function, it's just to keep track of how much the user has moved.
I managed to accomplish this with just else and if statements, no less! So I was wondering if you guys could give it a shot. The first if statement in each key if statement is so the user can't leave the canvas box. Then I have a function that moves the user by redrawing the canvas.
function redraw() {
clear(draw);
draw.fillStyle = 'rgba(0,0,0,0.5)';
draw.fillRect(left + right, up + down, '100', '100');
}
The "clear" function is just a simple function that clears the entire canvas. This is all controlled by an init function that looks like this:
function init() {
canvas = document.getElementById('game');
HEIGHT = canvas.height;
WIDTH = canvas.width;
draw = canvas.getContext('2d');
setInterval(redraw, 30);
document.onkeydown = canvasMove;
}
Your -check flags need to be global variables rather than function-scoped variables, otherwise they will never stay set between keydown events (handling only one key at a time). You also need a keyup event handler that will unset the correct flag when a key is released.
I've been wondering if there was a simple way to detect if a user presses the same character on the keyboard twice within one second. I've written some code that kind of works but it's unreliable.
var escapeCount = 0;
function reset() {
escapeCount = 0;
setTimeout('reset();', 1000);
}
window.onload = function() {
reset();
};
document.onkeyup = function(e) {
if (!e) var e = window.event;
var code = e.keyCode ? e.keyCode : e.which;
if (code == 27) escapeCount +=1;
if (escapeCount == 2) {
// stuff on second escape
}
};
Is there a better way to do this? Thanks
It would make sense to reset after 1 second has passed since the last character was pressed. Example:
var lastChar = -1;
document.onkeyup = function(e) {
if (!e) var e = window.event;
var code = e.keyCode ? e.keyCode : e.which;
if (lastChar == code) {
// Same key was pressed twice in a row within 1 second.
} else {
lastChar = code;
setTimeout(function() {lastChar = -1;}, 1000);
}
};
Your timer resets every second, so you not only have to press Escape again within a second of the last Escape, but that also has to have no timeout in between the presses.
It's probably easier to forget the timeout and just remember the time of the last keypress instead:
var lastescapetime= null;
document.onkeyup= function(event) {
if (event===undefined) event= window.event;
if (event.keyCode===27) {
var now= new Date().getTime();
if (lastescapetime!==null && now<lastescapetime+1000) {
alert('You double-escaped!');
lastescapetime= null;
} else {
lastescapetime= now;
}
} else {
lastescapetime= null;
}
};