Odd javascript bug
Post: #1
Hi,
I've been tricking around with HTML5 and I'm making a snake clone. When ever a piece of food is eaten the code calculates a new empty location in the world. This works fine for a good portion (~90%) of the play testing I've done so far.
However, at seemingly random points food items stop being placed in the world and when I check the javascript console (Chrome's developer tools) I get an error message that reads
It's not always '5' either so there's no pattern there. The game continues to play (everything is rendered and I can move the snake around) but no more food appears on screen.
I'm using a 2D array (an array of arrays) to represent the game world in grid form. My code for placing a new food item is:
Does anyone have any ideas?
Thanks,
Anthony
I've been tricking around with HTML5 and I'm making a snake clone. When ever a piece of food is eaten the code calculates a new empty location in the world. This works fine for a good portion (~90%) of the play testing I've done so far.
However, at seemingly random points food items stop being placed in the world and when I check the javascript console (Chrome's developer tools) I get an error message that reads
Quote:"Uncaught TypeError: Cannot read property '5' of undefined"
It's not always '5' either so there's no pattern there. The game continues to play (everything is rendered and I can move the snake around) but no more food appears on screen.
I'm using a 2D array (an array of arrays) to represent the game world in grid form. My code for placing a new food item is:
Code:
// find a row and column in the world that is empty
function FindFreeLocation()
{
var _r;
var _c;
do
{
_r = GenerateRandomNumber(0, worldWidth);
_c = GenerateRandomNumber(0, worldHeight);
} while (world[_r][_c] != 0); // error is generated here!
return {row:_r, col:_c};
}
function GenerateRandomNumber(min, max)
{
// var range = max – min + 1;
var range = max - min + 1;
// .floor() a bit more 'random' than round...
return Math.floor(Math.random() * range + min);
}Does anyone have any ideas?
Thanks,
Anthony
Post: #2
GenerateRandomNumber(0, N) sometimes returns N. You should either pass worldWidth - 1 & worldHeight - 1, or you should set range to max - min (no + 1) in GenerateRandomNumber.
Post: #3(Nov 27, 2010 01:22 PM)OneSadCookie Wrote: GenerateRandomNumber(0, N) sometimes returns N. You should either pass worldWidth - 1 & worldHeight - 1, or you should set range to max - min (no + 1) in GenerateRandomNumber.
D'oh
I can't believe I didn't pick that up. I ran a few tests and that's solved the problem. Thank you very much!
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