What is wrong with this Javascript? shopping cart

Question

There is something in this javascript or html which is is allowing the checkboxes to be ticked but for not even half a second. (I need the checks to stay there!) I also need the

Answer 1

Half of your if statements are missing parentheses, that's some basic wrongfulness.

I don't know what and where should any of the variables be, but here is my best shot:

function addItems(field) {
    var i;
    for (i = 0; i < field.length; i++) {
        if (field[i].checked === true) {
            if (computer[i] !== null) { 
                selected[i] = computer[i];
            }
        }
    }
}