I want the box to traverse the inside of the container from left to right, then down, then right to left and finally back up to the original position. The examples I found all include extra array pos = [180,180]. I don't understand why do I need it when my IF conditions seem to cover all positions.
window.onload = function() {
var t = setInterval(slide, 5);
pos1 = [0, 0];
var box = document.getElementById('sqr');
function slide() {
if (pos1[0] < 180 && pos1[1] < 180) {
pos1[0]++;
box.style.left = pos1[0] + "px";
} else if (pos1[0] >= 180 && pos1[1] < 180) {
pos1[1]++;
box.style.top = pos1[1] + "px";
} else if (pos1[0] >= 180 && pos1[1] >= 180) {
pos1[0]--;
box.style.left = pos1[0] + "px";
} else if (pos1[0] <= 0 && pos1[1] >= 180) {
pos1[1]--;
box.style.top = pos1[1] + "px";
}
}
}
#contain {
position: relative;
width: 200px;
height: 200px;
background-color: pink;
}
#sqr {
position: absolute;
width: 20px;
height: 20px;
background-color: blue;
}
<div id="contain">
<div id="sqr"></div>
</div>
Once the box gets to the maximum X and Y positions, the program is still checking to make sure the box hasn't reached the maximum yet, which causes the all IF conditions to fail. You could do it by checking for Y=0 for the first "leg", X=MAX for the next, Y=MAX for the next, and then X=0 for the last, but instead of that, you can set a "state" which has 4 values to determine which "leg" of the animation is being run, and then just run it for 180 iterations each.
window.onload = function() {
var t = setInterval(slide, 5);
pos1 = [0, 0];
var box = document.getElementById('sqr');
state = 0;
iterations = 0;
function slide() {
if (iterations >= 180) {state = (state + 1) % 4; iterations = 0;}
if (state === 0) pos1[0]++;
else if (state == 1) pos1[1]++;
else if (state == 2) pos1[0]--;
else if (state == 3) pos1[1]--;
iterations++;
box.style.left = pos1[0] + "px";
box.style.top = pos1[1] + "px";
}
}
#contain {
position: relative;
width: 200px;
height: 200px;
background-color: pink;
}
#sqr {
position: absolute;
width: 20px;
height: 20px;
background-color: blue;
}
<div id="contain">
<div id="sqr"></div>
</div>
window.onload = function() {
var t = setInterval(slide, 5);
var box = document.getElementById('sqr');
var left = 0,
top = 0;
function slide() {
var pos1 = [parseInt(box.style.left || 0), parseInt(box.style.top || 0)]
console.log(pos1);
if (pos1[0] == 0 && pos1[1] == 0) { //Top left, go right
left = 1;
top = 0;
} else if (pos1[0] == 180 && pos1[1] == 0) { //Top right, go down
left = 0;
top = 1;
} else if (pos1[0] == 180 && pos1[1] == 180) { //Bottom right, go left
left = -1;
top = 0;
} else if (pos1[0] == 0 && pos1[1] == 180) { //Bottom left, go up
left = 0;
top = -1;
}
box.style.left = (parseInt(box.style.left || 0) + left) + "px";
box.style.top = (parseInt(box.style.top || 0) + top) + "px";
}
}
#contain {
position: relative;
width: 200px;
height: 200px;
background-color: pink;
}
#sqr {
position: absolute;
width: 20px;
height: 20px;
background-color: blue;
}
<div id="contain">
<div id="sqr"></div>
</div>
Here's my take on it. React according to the position of the element, when it reaches a corner, change directions. This makes things easier, since we do not rely on actual positions to know where to go next step...
It is because, when animation gets to pos1 = [180, 180], it executes:
else if (pos1[0] >= 180 && pos1[1] >= 180) {
pos1[0]--;
box.style.left = pos1[0] + "px";
}
And then pos1 = [179, 180], which is not covered by the code.
I suggest using something like that:
var direction = 0; //0 - right, 1 - down, 2 - left, 3 - up
function slide() {
if (pos1[0] < 180 && pos1[1] = 0) {
direction = 0;
} else if (pos1[0] = 180 && pos1[1] < 180) {
direction = 1;
} else if (pos1[0] > 0 && pos1[1] = 180) {
direction = 2;
} else if (pos1[0] = 0 && pos1[1] > 0) {
direction = 3;
}
switch(direction){
case 0:
pos1[0]++;
break;
case 1:
pos1[1]++;
break;
case 2:
pos1[0]--;
break;
case 3:
pos1[1]--;
break;
}
box.style.left = pos1[0] + "px";
box.style.top = pos1[1] + "px";
}
I'm not usually a fan of doing someone's homework for them, but I got intrigued as to what would make it work and couldn't help myself. shrugs
The if statements have been tailored to be more explicit with what they need. This of course was achieved by following the methods suggested to you by #j08691, by just adding a console.log(pos1); at the top of each if section.
This is just for reference, in fact, #Salketer has managed to post before me and it looks a lot cleaner than this. The real answer is in the comments by #j08691
window.onload = function() {
var t = setInterval(slide, 5),
pos1 = [0, 0],
box = document.getElementById('sqr');
function slide() {
if (pos1[0] < 180 && pos1[1] === 0) {
console.log(pos1);
pos1[0]++;
box.style.left = pos1[0] + "px";
} else if (pos1[0] === 180 && pos1[1] < 180) {
console.log(pos1);
pos1[1]++;
box.style.top = pos1[1] + "px";
} else if ((pos1[0] <= 180 && pos1[0] >= 1) && pos1[1] === 180) {
console.log(pos1);
pos1[0]--;
box.style.left = pos1[0] + "px";
} else if (pos1[0] === 0 && pos1[1] <= 180) {
console.log(pos1);
pos1[1]--;
box.style.top = pos1[1] + "px";
}
}
}
#contain {
position: relative;
width: 200px;
height: 200px;
background-color: pink;
}
#sqr {
position: absolute;
width: 20px;
height: 20px;
background-color: blue;
}
<div id="contain">
<div id="sqr"></div>
</div>
Related
I am making an app for the Chrome Web Store. It is a clone of the Doodle Jump game. When I test and load it as an unpacked extension, this error keeps coming up.
Uncaught TypeError: Cannot read property 'getContext' of null
My code is here:
Javascript
function startGame() {
// RequestAnimFrame: a browser API for getting smooth animations
window.requestAnimFrame = (function() {
return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};
})();
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var width = 422,
height = 552;
canvas.width = width;
canvas.height = height;
//Variables for game
var platforms = [],
image = document.getElementById("sprite"),
player, platformCount = 10,
position = 0,
gravity = 0.2,
animloop,
flag = 0,
menuloop, broken = 0,
dir, score = 0, firstRun = true;
//Base object
var Base = function() {
this.height = 5;
this.width = width;
//Sprite clipping
this.cx = 0;
this.cy = 614;
this.cwidth = 100;
this.cheight = 5;
this.moved = 0;
this.x = 0;
this.y = height - this.height;
this.draw = function() {
try {
ctx.drawImage(image, this.cx, this.cy, this.cwidth, this.cheight, this.x, this.y, this.width, this.height);
} catch (e) {}
};
};
var base = new Base();
//Player object
var Player = function() {
this.vy = 11;
this.vx = 0;
this.isMovingLeft = false;
this.isMovingRight = false;
this.isDead = false;
this.width = 55;
this.height = 40;
//Sprite clipping
this.cx = 0;
this.cy = 0;
this.cwidth = 110;
this.cheight = 80;
this.dir = "left";
this.x = width / 2 - this.width / 2;
this.y = height;
//Function to draw it
this.draw = function() {
try {
if (this.dir == "right") this.cy = 121;
else if (this.dir == "left") this.cy = 201;
else if (this.dir == "right_land") this.cy = 289;
else if (this.dir == "left_land") this.cy = 371;
ctx.drawImage(image, this.cx, this.cy, this.cwidth, this.cheight, this.x, this.y, this.width, this.height);
} catch (e) {}
};
this.jump = function() {
this.vy = -8;
document.getElementById('audio').innerHTML='<audio src="sounds/pup.mp3" preload="auto" autoplay autobuffer></audio>'
};
this.jumpHigh = function() {
this.vy = -16;
document.getElementById('audio').innerHTML='<audio src="sounds/high.mp3" preload="auto" autoplay autobuffer></audio>'
};
};
player = new Player();
//Platform class
function Platform() {
this.width = 70;
this.height = 17;
this.x = Math.random() * (width - this.width);
this.y = position;
position += (height / platformCount);
this.flag = 0;
this.state = 0;
//Sprite clipping
this.cx = 0;
this.cy = 0;
this.cwidth = 105;
this.cheight = 31;
//Function to draw it
this.draw = function() {
try {
if (this.type == 1) this.cy = 0;
else if (this.type == 2) this.cy = 61;
else if (this.type == 3 && this.flag === 0) this.cy = 31;
else if (this.type == 3 && this.flag == 1) this.cy = 1000;
else if (this.type == 4 && this.state === 0) this.cy = 90;
else if (this.type == 4 && this.state == 1) this.cy = 1000;
ctx.drawImage(image, this.cx, this.cy, this.cwidth, this.cheight, this.x, this.y, this.width, this.height);
} catch (e) {}
};
//Platform types
//1: Normal
//2: Moving
//3: Breakable (Go through)
//4: Vanishable
//Setting the probability of which type of platforms should be shown at what score
if (score >= 5000) this.types = [2, 3, 3, 3, 4, 4, 4, 4];
else if (score >= 2000 && score < 5000) this.types = [2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4];
else if (score >= 1000 && score < 2000) this.types = [2, 2, 2, 3, 3, 3, 3, 3];
else if (score >= 500 && score < 1000) this.types = [1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3];
else if (score >= 100 && score < 500) this.types = [1, 1, 1, 1, 2, 2];
else this.types = [1];
this.type = this.types[Math.floor(Math.random() * this.types.length)];
//We can't have two consecutive breakable platforms otherwise it will be impossible to reach another platform sometimes!
if (this.type == 3 && broken < 1) {
broken++;
} else if (this.type == 3 && broken >= 1) {
this.type = 1;
broken = 0;
}
this.moved = 0;
this.vx = 1;
}
for (var i = 0; i < platformCount; i++) {
platforms.push(new Platform());
}
//Broken platform object
var Platform_broken_substitute = function() {
this.height = 30;
this.width = 70;
this.x = 0;
this.y = 0;
//Sprite clipping
this.cx = 0;
this.cy = 554;
this.cwidth = 105;
this.cheight = 60;
this.appearance = false;
this.draw = function() {
try {
if (this.appearance === true) ctx.drawImage(image, this.cx, this.cy, this.cwidth, this.cheight, this.x, this.y, this.width, this.height);
else return;
} catch (e) {}
};
};
var platform_broken_substitute = new Platform_broken_substitute();
//Spring Class
var spring = function() {
this.x = 0;
this.y = 0;
this.width = 26;
this.height = 30;
//Sprite clipping
this.cx = 0;
this.cy = 0;
this.cwidth = 45;
this.cheight = 53;
this.state = 0;
this.draw = function() {
try {
if (this.state === 0) this.cy = 445;
else if (this.state == 1) this.cy = 501;
ctx.drawImage(image, this.cx, this.cy, this.cwidth, this.cheight, this.x, this.y, this.width, this.height);
} catch (e) {}
};
};
var Spring = new spring();
function init() {
//Variables for the game
var dir = "left",
jumpCount = 0;
firstRun = false;
//Function for clearing canvas in each consecutive frame
function paintCanvas() {
ctx.clearRect(0, 0, width, height);
}
//Player related calculations and functions
function playerCalc() {
if (dir == "left") {
player.dir = "left";
if (player.vy < -7 && player.vy > -15) player.dir = "left_land";
} else if (dir == "right") {
player.dir = "right";
if (player.vy < -7 && player.vy > -15) player.dir = "right_land";
}
//Adding keyboard controls
document.onkeydown = function(e) {
var key = e.keyCode;
if (key == 37) {
dir = "left";
player.isMovingLeft = true;
} else if (key == 39) {
dir = "right";
player.isMovingRight = true;
}
if(key == 32) {
if(firstRun === true)
init();
else
reset();
}
};
document.onkeyup = function(e) {
var key = e.keyCode;
if (key == 37) {
dir = "left";
player.isMovingLeft = false;
} else if (key == 39) {
dir = "right";
player.isMovingRight = false;
}
};
//Accelerations produces when the user hold the keys
if (player.isMovingLeft === true) {
player.x += player.vx;
player.vx -= 0.15;
} else {
player.x += player.vx;
if (player.vx < 0) player.vx += 0.1;
}
if (player.isMovingRight === true) {
player.x += player.vx;
player.vx += 0.15;
} else {
player.x += player.vx;
if (player.vx > 0) player.vx -= 0.1;
}
//Jump the player when it hits the base
if ((player.y + player.height) > base.y && base.y < height) player.jump();
//Gameover if it hits the bottom
if (base.y > height && (player.y + player.height) > height && player.isDead != "lol") {
player.isDead = true;
document.getElementById('audio').innerHTML='<audio src="sounds/gameover.mp3" preload="auto" autoplay autobuffer></audio>'
}
//Make the player move through walls
if (player.x > width) player.x = 0 - player.width;
else if (player.x < 0 - player.width) player.x = width;
//Movement of player affected by gravity
if (player.y >= (height / 2) - (player.height / 2)) {
player.y += player.vy;
player.vy += gravity;
}
//When the player reaches half height, move the platforms to create the illusion of scrolling and recreate the platforms that are out of viewport...
else {
platforms.forEach(function(p, i) {
if (player.vy < 0) {
p.y -= player.vy;
}
if (p.y > height) {
platforms[i] = new Platform();
platforms[i].y = p.y - height;
}
});
base.y -= player.vy;
player.vy += gravity;
if (player.vy >= 0) {
player.y += player.vy;
player.vy += gravity;
}
score++;
}
//Make the player jump when it collides with platforms
collides();
if (player.isDead === true) gameOver();
}
//Spring algorithms
function springCalc() {
var s = Spring;
var p = platforms[0];
if (p.type == 1 || p.type == 2) {
s.x = p.x + p.width / 2 - s.width / 2;
s.y = p.y - p.height - 10;
if (s.y > height / 1.1) s.state = 0;
s.draw();
} else {
s.x = 0 - s.width;
s.y = 0 - s.height;
}
}
//Platform's horizontal movement (and falling) algo
function platformCalc() {
var subs = platform_broken_substitute;
platforms.forEach(function(p, i) {
if (p.type == 2) {
if (p.x < 0 || p.x + p.width > width) p.vx *= -1;
p.x += p.vx;
}
if (p.flag == 1 && subs.appearance === false && jumpCount === 0) {
subs.x = p.x;
subs.y = p.y;
subs.appearance = true;
jumpCount++;
}
p.draw();
});
if (subs.appearance === true) {
subs.draw();
subs.y += 8;
}
if (subs.y > height) subs.appearance = false;
}
function collides() {
//Platforms
platforms.forEach(function(p, i) {
if (player.vy > 0 && p.state === 0 && (player.x + 15 < p.x + p.width) && (player.x + player.width - 15 > p.x) && (player.y + player.height > p.y) && (player.y + player.height < p.y + p.height)) {
if (p.type == 3 && p.flag === 0) {
p.flag = 1;
jumpCount = 0;
return;
} else if (p.type == 4 && p.state === 0) {
player.jump();
p.state = 1;
} else if (p.flag == 1) return;
else {
player.jump();
}
}
});
//Springs
var s = Spring;
if (player.vy > 0 && (s.state === 0) && (player.x + 15 < s.x + s.width) && (player.x + player.width - 15 > s.x) && (player.y + player.height > s.y) && (player.y + player.height < s.y + s.height)) {
s.state = 1;
player.jumpHigh();
}
}
function updateScore() {
var scoreText = document.getElementById("score");
scoreText.innerHTML = score;
}
function gameOver() {
platforms.forEach(function(p, i) {
p.y -= 12;
});
if(player.y > height/2 && flag === 0) {
player.y -= 8;
player.vy = 0;
}
else if(player.y < height / 2) flag = 1;
else if(player.y + player.height > height) {
showGoMenu();
hideScore();
player.isDead = "lol";
}
}
//Function to update everything
function update() {
paintCanvas();
platformCalc();
springCalc();
playerCalc();
player.draw();
base.draw();
updateScore();
}
menuLoop = function(){return;};
animloop = function() {
update();
requestAnimFrame(animloop);
};
animloop();
hideMenu();
showScore();
}
function reset() {
hideGoMenu();
showScore();
player.isDead = false;
flag = 0;
position = 0;
score = 0;
base = new Base();
player = new Player();
Spring = new spring();
platform_broken_substitute = new Platform_broken_substitute();
platforms = [];
for (var i = 0; i < platformCount; i++) {
platforms.push(new Platform());
}
}
//Hides the menu
function hideMenu() {
var menu = document.getElementById("mainMenu");
menu.style.zIndex = -1;
}
//Shows the game over menu
function showGoMenu() {
var menu = document.getElementById("gameOverMenu");
menu.style.zIndex = 1;
menu.style.visibility = "visible";
var scoreText = document.getElementById("go_score");
scoreText.innerHTML = "Ваш результат " + score + " очков!";
}
//Hides the game over menu
function hideGoMenu() {
var menu = document.getElementById("gameOverMenu");
menu.style.zIndex = -1;
menu.style.visibility = "hidden";
}
//Show ScoreBoard
function showScore() {
var menu = document.getElementById("scoreBoard");
menu.style.zIndex = 1;
}
//Hide ScoreBoard
function hideScore() {
var menu = document.getElementById("scoreBoard");
menu.style.zIndex = -1;
}
function playerJump() {
player.y += player.vy;
player.vy += gravity;
if (player.vy > 0 &&
(player.x + 15 < 260) &&
(player.x + player.width - 15 > 155) &&
(player.y + player.height > 475) &&
(player.y + player.height < 500))
player.jump();
if (dir == "left") {
player.dir = "left";
if (player.vy < -7 && player.vy > -15) player.dir = "left_land";
} else if (dir == "right") {
player.dir = "right";
if (player.vy < -7 && player.vy > -15) player.dir = "right_land";
}
//Adding keyboard controls
document.onkeydown = function(e) {
var key = e.keyCode;
if (key == 37) {
dir = "left";
player.isMovingLeft = true;
} else if (key == 39) {
dir = "right";
player.isMovingRight = true;
}
if(key == 32) {
if(firstRun === true) {
init();
firstRun = false;
}
else
reset();
}
};
document.onkeyup = function(e) {
var key = e.keyCode;
if (key == 37) {
dir = "left";
player.isMovingLeft = false;
} else if (key == 39) {
dir = "right";
player.isMovingRight = false;
}
};
//Accelerations produces when the user hold the keys
if (player.isMovingLeft === true) {
player.x += player.vx;
player.vx -= 0.15;
} else {
player.x += player.vx;
if (player.vx < 0) player.vx += 0.1;
}
if (player.isMovingRight === true) {
player.x += player.vx;
player.vx += 0.15;
} else {
player.x += player.vx;
if (player.vx > 0) player.vx -= 0.1;
}
//Jump the player when it hits the base
if ((player.y + player.height) > base.y && base.y < height) player.jump();
//Make the player move through walls
if (player.x > width) player.x = 0 - player.width;
else if (player.x < 0 - player.width) player.x = width;
player.draw();
}
function update() {
ctx.clearRect(0, 0, width, height);
playerJump();
}
menuLoop = function() {
update();
requestAnimFrame(menuLoop);
};
menuLoop();
}
document.addEventListener("DOMContentLoaded", startGame, false);
<!DOCTYPE HTML>
<html>
<head>
<title>Doodle Jump</title>
<style type="text/css">
#import url(Gloria%20Hallelujah);
*{box-sizing: border-box;}
body {
margin: 0; padding: 0;
font-family: 'Gloria Hallelujah', cursive;
}
.container {
height: 552px;
width: 422px;
position: relative;
margin: 20px auto;
overflow: hidden;
}
canvas {
height: 552px;
width: 422px;
display: block;
background: url(images/Y0BMP.png) top left;
}
#scoreBoard {
width: 420px;
height: 50px;
background: rgba(182, 200, 220, 0.7);
position: absolute;
top: -3px;
left: 0;
z-index: -1;
border-image: url(images/5BBsR.png) 100 5 round;
}
#scoreBoard p {
font-size: 20px;
padding: 0;
line-height: 47px;
margin: 0px 0 0 5px;
}
img {display: none}
#mainMenu, #gameOverMenu {
height: 100%;
width: 100%;
text-align: center;
position: absolute;
top: 0;
left: 0;
z-index: 2;
}
#gameOverMenu {
visibility: hidden;
}
h2, h3, h1 {font-weight: normal}
h1 {
font-size: 60px;
color: #5a5816;
transform: rotate(-10deg);
margin: 0px;
}
h3 {text-align: right; margin: -10px 20px 0 0; color: #5e96be}
h3 a {color: #5a5816}
.button {
width: 105px;
height: 31px;
background: url(images/2WEhF.png) 0 0 no-repeat;
display: block;
color: #000;
font-size: 12px;
line-height: 31px;
text-decoration: none;
position: absolute;
left: 50%;
bottom: 50px;
margin-left: -53px;
}
.info {position: absolute; right: 20px; bottom: 00px; margin: 0; color: green}
.info .key {
width: 16px;
height: 16px;
background: url(images/2WEhF.png) no-repeat;
text-indent: -9999px;
display: inline-block;
}
.info .key.left {background-position: -92px -621px;}
.info .key.right {background-position: -92px -641px;}
</style>
</head>
<body><div style="position:absolute;z-index:999;padding:10px;top:0;right:0;background:#000" id="sxz03">
<div style="float:right;padding-left:10px"><img onclick="document.getElementById('sxz03').style.display='none'" src="images/x.gif" width="15" alt="" /></div>
<br>
<div style="position:absolute;top:-100px"></div>
</div>
<div class="container">
<canvas id="canvas"></canvas>
<div id="mainMenu">
<h1>doodle jump</h1>
<h3>A HTML5 game</h3>
<a class="button" href="javascript:init()">Play</a>
</div>
<div id="gameOverMenu">
<h1>Game Over!</h1>
<h3 id="go_score">Your score was ...</h3>
<a class="button" href="javascript:reset()">Play Again</a>
</div>
<!-- Preloading image ;) -->
<img id="sprite" src="images/2WEhF.png"/>
<div id="scoreBoard">
<p id="score">0</p>
</div>
</div>
<div id="audio"></div>
<script src="jquery.min.js"></script>
<script src="game.js"></script>
</body>
</html>
So when I run this, the intro works, but when I click the play button, nothing happens. If you want to run this code, I will put a download link for the folder that I used in this question.
I just want to ask how to detect the mouse pointer come from using jquery when the pointer hover an element like div.
When run the function I want to know mouse pointer come from top, left, bottom and right
Thank you!
Try this code:
var getDirection = function (ev, obj) {
var w = obj.offsetWidth,
h = obj.offsetHeight,
x = (ev.pageX - obj.offsetLeft - (w / 2) * (w > h ? (h / w) : 1)),
y = (ev.pageY - obj.offsetTop - (h / 2) * (h > w ? (w / h) : 1)),
d = Math.round( Math.atan2(y, x) / 1.57079633 + 5 ) % 4;
return d;
};
$('#yourDiv').mouseover(function (event) {
var direction = getDirection(event, this);
if (direction == 0) {
$(this).html('Top side');
} else if (direction == 1) {
$(this).html('Right side');
} else if (direction == 2) {
$(this).html('Bottom side');
} else if (direction == 3) {
$(this).html('Left side');
}
});
#yourDiv {
width: 100px;
height: 100px;
background-color: red;
position: absolute;
top: 50px;
left: 50px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="yourDiv"></div>
getDirection copied from this page by CSS-Tricks which seems to do a similar thing to what you want in a number of different ways.
I am new in JavaScript, so I have some difficulties with it. I would like to move a small div within another bigger div with arrow keys - left, up, right and down. I have the code below but it does not work properly.
HTML and CSS
<div id="rectangle">
<div id="square"></div>
</div>
#rectangle {
width: 320px;
height: 200px;
border: 1px solid;
margin: auto;
position: relative;
}
#square {
width: 40px;
height: 40px;
background-color: deepskyblue;
position: absolute;
left: 0;
top:0;
}
Javascript
var rectangle = document.getElementById("rectangle");
var square = document.getElementById("square");
var currentPositionX = 0;
var currentPositionY = 0;
function moveSquare(event) {
if (event.keyCode == 37) {
currentPositionX -= 40;
square.style.left = currentPositionX + 'px';
if (currentPositionX <= 0) {
currentPositionX += 40;
}
}
if (event.keyCode == 38) {
currentPositionY -= 40;
square.style.top = currentPositionY + 'px';
if (currentPositionY <= 0) {
currentPositionY += 40;
}
}
if (event.keyCode == 39) {
currentPositionX += 40;
square.style.left = currentPositionX + 'px';
if (currentPositionX >= 280) {
currentPositionX -= 40;
}
}
if (event.keyCode == 40) {
currentPositionY += 40;
square.style.top = currentPositionY + 'px';
if (currentPositionY >= 160) {
currentPositionY -= 40;
}
}
}
document.onkeydown = moveSquare;
I have tested the code and found that when you are near the borders it's not working properly (Perhaps this was the original question?). On this i tested another simpler solution: I just changed your moveSquare function to only do work when you are inside your bounds (I mean, you shouldn't be always incrementing/decrementing position and then check if you are out of bounds to correct it).
function moveSquare(event) {
if (event.keyCode == 37) {
if (currentPositionX > 0) {
currentPositionX -= 40;
square.style.left = currentPositionX + 'px';
}
}
if (event.keyCode == 38) {
if (currentPositionY > 0) {
currentPositionY -= 40;
square.style.top = currentPositionY + 'px';
}
}
if (event.keyCode == 39) {
if (currentPositionX < 280) {
currentPositionX += 40;
square.style.left = currentPositionX + 'px';
}
}
if (event.keyCode == 40) {
if (currentPositionY < 160) {
currentPositionY += 40;
square.style.top = currentPositionY + 'px';
}
}
}
Here is the jsfiddle: https://jsfiddle.net/epL4a9Lq/
Please, next time be more specific on your error (i would comment this before answering but i have no reputation yet for that).
Hope this helps!
I'm trying to create a custom range slider. Everything works well besides for when you zoom in on the webpage, then reload. When I do that, the range slider (green background) doesn't drag to its correct position.
Here's the relevant code: (In function sliderMove line 30)
cursorPosition = ((e.touches && e.touches[0].clientX) || e.clientX) - startPoint.left;
rangePosition = clamp(cursorPosition, _sliderPositions.rangeStart, _sliderPositions.rangeEnd);
cursorPosition = clamp(cursorPosition - cursorRadius, _sliderPositions.cursorStart, _sliderPositions.cursorEnd);
What am I doing wrong, and how can I fix it?
JSFiddle
console.clear();
function RangeSlider( /** DOM Elem */ parentElem) {
var wrapperElem = document.getElementsByClassName('wrapperElem')[0],
slider = document.getElementsByClassName('slider')[0],
sliderRange = document.getElementsByClassName('sliderRange')[0],
sliderCursor = document.getElementsByClassName('sliderCursor')[0],
output = document.getElementById('output'),
myButton = document.getElementById('myButton');
var sliderDimention = slider.offsetWidth,
cursorRadius = sliderCursor.offsetHeight / 2,
startPoint,
currentTarget,
value = 0,
_sliderPositions = {},
borderWidth = 1;
startPoint = getOrigin(wrapperElem.children[0]);
sliderDimention = slider.offsetWidth;
function sliderDown(e) {
e.preventDefault();
window.addEventListener('mousemove', sliderMove);
sliderMove(e);
}
function sliderMove(e) {
var rangePosition = 0;
var cursorPosition = 0;
reconfigVars();
if (typeof e === 'object') {
cursorPosition = ((e.touches && e.touches[0].clientX) || e.clientX) - startPoint.left;
} else {
cursorPosition = pixelToPercent(value, 0, 500) / 100 * sliderDimention;
}
//console.log(cursorPosition);
rangePosition = clamp(cursorPosition, _sliderPositions.rangeStart, _sliderPositions.rangeEnd);
cursorPosition = clamp(cursorPosition - cursorRadius, _sliderPositions.cursorStart, _sliderPositions.cursorEnd);
sliderCursor.style.transform = 'translateX(' + cursorPosition + 'px)';
sliderRange.style.transform = 'scaleX(' + rangePosition + ')';
if (typeof e === 'object') {
value = percentToPixel((
(cursorPosition - _sliderPositions.cursorStart) / (_sliderPositions.currentValue - borderWidth * 2)
) * 100, 0, 500);
}
output.innerHTML = value;
}
function reconfigVars() {
_sliderPositions.rangeStart = borderWidth * 2;
_sliderPositions.rangeEnd = sliderDimention - borderWidth * 2
_sliderPositions.cursorStart = startPoint.left - cursorRadius + borderWidth * 2;
_sliderPositions.cursorEnd = sliderDimention - borderWidth * 2 - cursorRadius * 2;
_sliderPositions.currentValue = sliderDimention - borderWidth * 2 - startPoint.left - cursorRadius;
}
myButton.addEventListener('click', function() {
sliderMove(500);
value = 500;
});
function mouseUpEvents() {
window.removeEventListener('mousemove', sliderMove);
}
wrapperElem.addEventListener('mousedown', sliderDown);
window.addEventListener('mouseup', mouseUpEvents);
}
var sliderTest = document.getElementById('sliderTest');
var test = new RangeSlider(sliderTest);
function getOrigin(elm) {
var box = (elm.getBoundingClientRect) ? elm.getBoundingClientRect() : {
top: 0,
left: 0
},
doc = elm && elm.ownerDocument,
body = doc.body,
win = doc.defaultView || doc.parentWindow || window,
docElem = doc.documentElement || body.parentNode,
clientTop = docElem.clientTop || body.clientTop || 0, // border on html or body or both
clientLeft = docElem.clientLeft || body.clientLeft || 0;
return {
left: box.left + (win.pageXOffset || docElem.scrollLeft) - clientLeft,
top: box.top + (win.pageYOffset || docElem.scrollTop) - clientTop
};
}
function clamp(val, moreThan, lessThan) {
if (typeof lessThan === 'undefined') lessThan = 1;
if (typeof moreThan === 'undefined') moreThan = 0;
return Math.min(lessThan, Math.max(moreThan, val));
}
function pixelToPercent(pixel, min, max) {
if (typeof max === 'undefined') return;
return ((pixel - min) / (max - min)) * 100;
}
function percentToPixel(percent, min, max) {
if (typeof max === 'undefined') return;
return ((percent / 100) * (max - min)) + min;
}
.wrapperElem {
height: 18px;
width: 100%;
cursor: pointer;
display: flex;
}
.slider {
height: 100%;
width: calc(100% - 62px);
border: 1px solid black;
position: relative;
}
.sliderCursor {
width: 14px;
height: 14px;
border-radius: 50%;
border: 2px solid black;
}
.sliderRange {
background-color: green;
position: absolute;
width: 1px;
height: 100%;
transform-origin: left;
}
#output {
background-color: orange;
}
<div class="wrapperElem">
<div class="slider">
<div class="sliderRange"></div>
<div class="sliderCursor"></div>
</div>
</div>
<br />
<div id="output"></div>
<button id="myButton">Click Me</button>
I'm trying to create a custom range slider. I'm having trouble keeping the slidersCursor in the slider.
Here's the relevant code:
var cursorPosition = 1 - clamp01((sliderDimention - (e.clientX - startPoint.left)) / sliderDimention);
sliderCursor.style.transform = 'translateX(' + (cursorPosition * sliderDimention - cursorRadius) + 'px)';
With the code above, when you drag the slider to the far right or left, the cursor goes halfway out of the slider on either side.
When I remove - cursorRadius, it goes too much to the right side. It stays in the slider when you drag to the left, but when you drag it to the right, it goes out of the slider.
When cursorRadius is equal to cursor.offsetWidth, it goes too much to the left side.
How can I make the sliderCursor stay in the slider when you drag to the far sides?
(Please don't post any JQuery or other "you can use 'this' plugin" answers. I'm doing this for learning purposes, and I want to create my own. Thanks!)
JSFiddle
function RangeSlider( /** DOM Elem */ parentElem) {
var wrapperElem = document.getElementsByClassName('wrapperElem')[0],
slider = document.getElementsByClassName('slider')[0],
sliderCursor = document.getElementsByClassName('sliderCursor')[0];
var sliderDimention = slider.offsetWidth,
cursorRadius = sliderCursor.offsetHeight / 2,
startPoint,
currentTarget;
function sliderDown(e) {
e.preventDefault();
currentTarget = null;
var sliderWithDescendents = wrapperElem.querySelectorAll('*');
for (var i = 0; i < sliderWithDescendents.length; i++) {
sliderWithDescendents[i]
if (sliderWithDescendents[i] === e.target || wrapperElem === e.target) {
currentTarget = wrapperElem.children[0];
break;
}
}
if (currentTarget === null) return;
startPoint = getOrigin(currentTarget);
sliderDimention = slider.offsetWidth;
window.addEventListener('mousemove', sliderMove);
sliderMove(e);
}
function sliderMove(e) {
var cursorPosition = 1 - clamp01((sliderDimention - (e.clientX - startPoint.left)) / sliderDimention);
sliderCursor.style.transform = 'translateX(' + (cursorPosition * sliderDimention - cursorRadius) + 'px)';
}
function mouseUpEvents() {
window.removeEventListener('mousemove', sliderMove);
}
wrapperElem.addEventListener('mousedown', sliderDown);
window.addEventListener('mouseup', mouseUpEvents);
}
var sliderTest = document.getElementById('sliderTest');
var test = new RangeSlider(sliderTest);
function clamp01(val) {
return Math.min(1, Math.max(0, val));
}
function getOrigin(elm) {
var box = (elm.getBoundingClientRect) ? elm.getBoundingClientRect() : {
top: 0,
left: 0
},
doc = elm && elm.ownerDocument,
body = doc.body,
win = doc.defaultView || doc.parentWindow || window,
docElem = doc.documentElement || body.parentNode,
clientTop = docElem.clientTop || body.clientTop || 0, // border on html or body or both
clientLeft = docElem.clientLeft || body.clientLeft || 0;
return {
left: box.left + (win.pageXOffset || docElem.scrollLeft) - clientLeft,
top: box.top + (win.pageYOffset || docElem.scrollTop) - clientTop
};
}
.wrapperElem {
height: 18px;
width: 100%;
cursor: pointer;
display: flex;
}
.slider {
height: 100%;
width: calc(100% - 62px);
border: 1px solid black;
}
.sliderCursor {
width: 14px;
height: 14px;
border-radius: 50%;
border: 2px solid black;
}
<div class="wrapperElem">
<div class="slider">
<div class="sliderCursor"></div>
</div>
</div>
It should be sliderCursor.style.transform = 'translateX(' + (cursorPosition * (sliderDimention - cursorRadius*2)) + 'px)';
You need the radius times x2 then the brackets are to perform the operations first then multiply by cursorPostions (which is from 0 to 1);
Although it works, I'd try clamp the final value (from [0 + radius] to [dimension - radius]). That way you won't get this weird drag where the mouse is in the left or right of the scroll_cursor. You want the mouse to be in the center of it at all times.
If you are doing it for learning, dissect rangeslider.js? It's very well coded.
function RangeSlider( /** DOM Elem */ parentElem) {
var wrapperElem = document.getElementsByClassName('wrapperElem')[0],
slider = document.getElementsByClassName('slider')[0],
sliderCursor = document.getElementsByClassName('sliderCursor')[0];
var sliderDimention = slider.offsetWidth,
cursorRadius = sliderCursor.offsetHeight / 2,
startPoint,
currentTarget;
function sliderDown(e) {
e.preventDefault();
currentTarget = null;
var sliderWithDescendents = wrapperElem.querySelectorAll('*');
for (var i = 0; i < sliderWithDescendents.length; i++) {
sliderWithDescendents[i]
if (sliderWithDescendents[i] === e.target || wrapperElem === e.target) {
currentTarget = wrapperElem.children[0];
break;
}
}
if (currentTarget === null) return;
startPoint = getOrigin(currentTarget);
sliderDimention = slider.offsetWidth;
window.addEventListener('mousemove', sliderMove);
sliderMove(e);
}
function sliderMove(e) {
var cursorPosition = 1 - clamp01((sliderDimention - (e.clientX - startPoint.left)) / sliderDimention);
sliderCursor.style.transform = 'translateX(' + (cursorPosition * (sliderDimention - cursorRadius*2)) + 'px)';;
}
function mouseUpEvents() {
window.removeEventListener('mousemove', sliderMove);
}
wrapperElem.addEventListener('mousedown', sliderDown);
window.addEventListener('mouseup', mouseUpEvents);
}
var sliderTest = document.getElementById('sliderTest');
var test = new RangeSlider(sliderTest);
function clamp01(val) {
return Math.min(1, Math.max(0, val));
}
function getOrigin(elm) {
var box = (elm.getBoundingClientRect) ? elm.getBoundingClientRect() : {
top: 0,
left: 0
},
doc = elm && elm.ownerDocument,
body = doc.body,
win = doc.defaultView || doc.parentWindow || window,
docElem = doc.documentElement || body.parentNode,
clientTop = docElem.clientTop || body.clientTop || 0, // border on html or body or both
clientLeft = docElem.clientLeft || body.clientLeft || 0;
return {
left: box.left + (win.pageXOffset || docElem.scrollLeft) - clientLeft,
top: box.top + (win.pageYOffset || docElem.scrollTop) - clientTop
};
}
.wrapperElem {
height: 18px;
width: 100%;
cursor: pointer;
display: flex;
}
.slider {
height: 100%;
width: calc(100% - 62px);
border: 1px solid black;
}
.sliderCursor {
width: 14px;
height: 14px;
border-radius: 50%;
border: 2px solid black;
}
<div class="wrapperElem">
<div class="slider">
<div class="sliderCursor"></div>
</div>
</div>