generate sequential strings in javascript

Question

Im making a javascript game, and I want to generate enemies, but this does not seem to work

var Monster = function(x,y) {
 this.x = x;
 this.y = y;
};
var spawnMonsters = function() {
 for(var i = 0; i < spawn; i++) {
 var name = "Monster";
 name += i;
 name = new Monster(Math.random()*canvas.width-16,0); 
 } 
};

help please? Though I can generate multiple enemies by hard-coding each monster name. such as Monster2=new Monster(Math.random()*canvas.width-16,0); Monster3=...... etc

• Evan Davis: What does not seem to work? What do you expect your code to do vs what is happening?

Answer 1

In javascript you cannot use "variable variables" as you could do, for example, in PHP.

You could try this:

var monsters = [];
function spawn(num) {
 for (var i = 0; i < num; ++i) {
 monster.push(new Monster(Math.random() * canvas.width - 16, 0));
 }
}

now monsters will be an array of all the monsters you spawned.

• drquicksilver: Well you can use variable variables, either by using eval or by poking them into the scope object concerned (e.g. window in a browser). However you shouldn't do that for various reasons, so this approach is a much better one.
• Jamie Anacleto: Thanks Matteo! lastly, how can I use that array of monsters to be drawn by this function var drawMonsters=function(){ for (var i=0;i<spawn;i++){ var name = "Monster"; name+=i; ctx.drawImage(monsterImage, name.x, name.y); } }
• Matteo Tassinari: In your function, it is not clear from where monsterImage does come.

Answer 2

You can genarate Strings like:

function makeid()
{
var text = "";
var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
for( var i=0; i < 5; i++ )
 text += possible.charAt(Math.floor(Math.random() * possible.length));
return text;
}