Question

I have no idea about loop in jquery. I want the following code to be run as for loop from product1 to product20 and check the same if quantity1 to quantity20 have no value then set it to 1.

$('#product1').change(function() {
    if(  $('#quantity1').val().length == 0 ){
        $('#quantity1').val("1");
    }
});

$('#product2').change(function() {
    if(  $('#quantity2').val().length == 0 ){
        $('#quantity2').val("1");
    }
});

Thank you in advance.

Answer 1

I think that the each method is the best solution here, as you need an anonymous function anyway to create a closuse that holds the value for each iteration (as the event handler runs later, each one needs its own version of the loop counter):

$.each(new Array(20), function(i){
  $('#product' + (i+1)).change(function() {
    var q = $('#quantity' + (i+1));
    if (q.val().length == 0 ){
      q.val("1");
    }
  });
});