Bomberman clone, how to do bombs?

It doesn't look that bad, but you need better control of timing and input. As it is movement speed is dependent on the keystroke repetition setting on the users machine, that is not exactly optimal.

Instead you should track which keys are currently being held down, you can do this like (in pseudocode):

keyisdown=false keydown event{ if(!keyisdown){ //This is the 'real' keydown event, the one that only happens the moment the //key is pressed down. You may not need it, but this is how you construct it. } keyisdown=true } keyup event{ keyisdown=false } 

And then in your update function you move the player if keyisdown, and possibly you apply some other conditions, like the player can't move if he moved less than some number of updates ago.

Keep an updated counter or some other way of keeping track of time so that your code always know exactly how far progressed it should be.

Da bomb
Personally I'd keep it simple, you don't actually need to use this, new and all the other fancy stuff in JavaScript to make useful objects.

You could do something like:

bombobject = {} //That is all it takes to make an object. bombobject.blowtime = currenttime + delay bombobject.position = mapobject mapobject.bomb = bombobject 

Then you can cycle through the map on every update, check if there is a bomb and if it's time to blow, if so blow and remove the bomb object.

Bugtracking
Your code is leaking errors, they are pretty simple, but if you don't learn about them and handle them you are going to have problems later on. Every modern browser has a Firebug clone developer console. Open it, look at the script console tab, see all the nasty red text and fix it.

Edit: Timekeeping concerns
Just for the record, you'd probably want something slightly more advanced than setInterval for timing, if you are serious you really need to make your code adjust for the timeslip. See my very first Stack Overflow answer for an approximate description of the problem: https://stackoverflow.com/a/2549426/305545

Edit: setTimeOut version fixed
Since you are using the same variables for different bombs you are going to overwrite them whenever a new bomb is placed. You can use a closure to make individual variables for each bomb, like so:

function placeBomb(){ if(placebomb && player.bombs != 0){ map[player.Y][player.X].object = 2; var bombX = player.X; var bombY = player.Y; placebomb = false; player.bombs--; setTimeout(explode, 3000); } function explode(){ alert('BOOM!'); delete map[bombY][bombX].object; player.bombs++; } } 

Now the bombX and bombY variables and the explode function are locals to the closure created by placeBombs, thus it is the local instance of explode that is attached to the timeout, and it reads the local variables. Each time you call placeBomb a new closure is created.

I wouldn't have used setTimeout for this, I would have counted updates, thus ensuring a fixed number of updates before the bomb blows, but I guess this will work ok.