javascript for循环行为异常

Question

I know this is really basic but I am new to Javascript

This is a piece of code from a battleship game I am working on for a class

function displayMyBoats(ship){

    for (var i = 0; i<ship.length; i++) 
    {
        alert("ship.length = " + ship.length);
        alert("Ship[i]= " + ship[i]);
        document.getElementById( "Set_" + ship[i] ).src = fnImageShip;
        alert("i = " + i);
    }
}

I am testing with a ship array that is 5 elements. Everything works fine until it reaches 5, then all of a sudden it thinks the length of the array is 8.

There is no code to increase the length of ship array, so what would cause it to add to the length of the array?

The alerts are my testing to see what all the values are at.

Answer 1

To give you a hint, try adding an alert whenever your script is either entering or exiting the displayMyBoats() . Suddenly jumping to 8 indicates that it's entering the method a second time, this time with a ship of len 8.

Confirm or deny this theory by adding this alert after your for loop block:

 alert('exiting displayMyBoats()');`

Answer 2

Perhaps you see more if you use console.log(ship); instead of alert(); - if you are using Firebug/Console.