i have written a snake program using javascript.. the problem is that the snake does not grow more than 2 blocks size....
<html>
<head>
<script type="text/javascript">
var matrix, body, dir, key, lastx, lasty, start, applex, appley, eat, hal;
function node(x, y) {
this.x = x;
this.y = y;
}
function draw() {
var str;
for (var i = 0; i < body.length; i++) {
matrix[body[i].x * 50 + body[i].y].bgColor = "black";
}
}
function halt() {
hal = 1 - hal;
if (hal == 0) automove();
}
function check_status() {
if (start == 1 && hal == 0) {
var ch;
if (eat == 1) {
do {
ch = 0;
applex = Math.round(49 * Math.random());
appley = Math.round(49 * Math.random());
for (var i = 0; i < body.length; i++)
if (body[i].x == applex && body[i].x == appley) ch = 1;
} while (ch == 1);
matrix[applex * 50 + appley].bgColor = "blue";
eat = 0;
}
lastx = body[body.length - 1].x;
lasty = body[body.length - 1].y;
for (var i = 1; i < body.length; i++) {
body[i].x = body[i - 1].x;
body[i].y = body[i - 1].y;
}
if (dir == 1)--body[0].x;
else if (dir == -1)++body[0].x;
else if (dir == 2)--body[0].y;
else if (dir == -2)++body[0].y;
if (body[0].x == -1 || body[0].x == 50 || body[0].y == 50 || body[0].y == -1) {
alert("GAME OVER!!");
start = 0;
}
for (var i = 1; i < body.length; i++) {
if (body[0].x == body[i].x && body[0].y == body[i].y) {
alert("GAME OVER!!");
start = 0;
i = 10000;
}
}
if (body[0].x == applex && appley == body[0].y) {
eat = 1;
body[body.length] = new node(lastx, lasty);
}
matrix[lastx * 50 + lasty].bgColor = "white";
draw();
}
}
function automove() {
if (start == 1 && hal == 0) {
if (key != -dir) dir = key;
check_status();
window.setTimeout("automove()", 200);
}
}
function init() {
start = 1;
var x = document.getElementById("mine");
var str = "<table id='tab' align='center' height='500px' cellSpacing='0' cellPadding='0' width='500px' border='4' >";
for (var i = 0; i < 50; i++) {
str += "<tr>";
for (var j = 0; j < 50; j++)
str += "<td></td>";
str += "</tr>";
}
str += "</table>";
x.innerHTML = str;
matrix = document.getElementsByTagName("td");
body = new Array();
body[0] = new node(0, 0);
draw();
dir = key = -1;
eat = 1;
v = 0;
hal = 0;
automove();
}
function keypress(e) {
if ((e.keyCode == 38) || ((e.which) && (e.which == 38))) //up
key = 1;
else if ((e.keyCode == 40) || ((e.which) && (e.which == 40))) //down
key = -1;
else if ((e.keyCode == 37) || ((e.which) && (e.which == 37))) //left
key = 2;
else if ((e.keyCode == 39) || ((e.which) && (e.which == 39))) //right
key = -2;
check_status();
}
</script>
</head>
<body onkeydown=keypress(event)>
<br/>
<input type="button" onClick="init()" value="play">
<input type="button" onClick="halt()" value="pause">
<p id="mine"></p>
<br><h5 id="score"></h5>
</body>
</html>
Russ Cam
126k34 gold badges211 silver badges275 bronze badges
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I don't fancy deciphering that. Please can you indent it (+ 4 spaces before each line)?Jhong– Jhong2010年08月01日 15:19:42 +00:00Commented Aug 1, 2010 at 15:19
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1You should get into the practice of adding comments to your code as and when you write it. Code such as this (involving lot of maths) can quickly become confusing even to its original author.casablanca– casablanca2010年08月01日 15:25:49 +00:00Commented Aug 1, 2010 at 15:25
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1jsbeautifier.org to the rescue!Russ Cam– Russ Cam2010年08月01日 15:29:08 +00:00Commented Aug 1, 2010 at 15:29
1 Answer 1
The problem is here:
lastx=body[body.length-1].x;
lasty=body[body.length-1].y;
for(var i=1;i<body.length;i++)
{
body[i].x=body[i-1].x;
body[i].y=body[i-1].y;
}
In that loop, body[1] is assigned to body[0], then body [2] is assigned to body[1] etc. This means that everything from index 1 to the end will be set equal to body[0], then body[0] is altered based on direction - so there are only two positions.
Look into the javascript unshift method.
You could replace that loop with:
body.unshift(body[0]);
answered Aug 1, 2010 at 15:26
sje397
41.9k9 gold badges90 silver badges106 bronze badges
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1 Comment
psy
did this program while i was feeling sleepy. KILL ME for making this dumb error!!
lang-js