Text field validation Using Jquery

I have 5 text field in 5 rows like this..

<div class="dt_distance_slab">
     <g:textField class ="number distanceSlab1" name="distanceSlabCost1" id = "distanceSlabCost1"  value=""/> 
  </div>
<div class="dt_distance_slab">
     <g:textField class ="number distanceSlab2" name="distanceSlabCost2" id = "distanceSlabCost2"  value=""/> 
  </div>
  <div class="dt_distance_slab">
     <g:textField class ="number distanceSlab3" name="distanceSlabCost3" id = "distanceSlabCost3"  value=""/> 
  </div>
   <div class="dt_distance_slab">
     <g:textField class ="number distanceSlab4" name="distanceSlabCost4" id = "distanceSlabCost4"  value=""/> 
  </div>
    <div class="dt_distance_slab">
     &l开发者_如何学运维t;g:textField class ="number distanceSlab5" name="distanceSlabCost5" id = "distanceSlabCost5"  value=""/> 
  </div>

here all fields are optional.. i want to put validation like if user wants to enter the value.. he cannot skip a row in between ... if he want to enter value for a text field ,previous text field must have value..

validation will be done on submitting the form

Would you get a better user experience by preventing input in the fields that doesn't have a preceeding value? If all the fields except the first one is disabled by default, you could enable the next one on the blur event.

$('input:gt(1)').attr('disabled','disabled');
var fields = $('input');
$('input').blur(function(){
  var $this = $(this);
  if($this.val() != ''){
    fields.eq($this.index()+1).attr('disabled','');
  }
});

Try with this code:

$(document).ready(function(){
    //assuming the validation fires on the click of a button
    $("#btnSubmit").click(function(){ 
        //set valid variable to true
        var blnIsValid = true;
        //loop through each of the text boxes
        $(":text[class^='number']").each(function(i){
            //start validating from the second text box
            if(i > 0) {
                var curTxtBox = $(this);
                var prevTxtBox =  $(":text[class^='number']:eq("+ (i-1) +")");
                if($.trim(curTxtBox.val()) != "" && $.trim(prevTxtBox.val()) == "") {
                    alert("Enter value for previous distance");
                    //set focus on the text box
                    prevTxtBox.focus();
                    //set valid variable to false
                    blnIsValid = false;
                    //exit the loop
                    return false;
                }
            }
        });
        return blnIsValid;
    });
});

Here's a working example in jsFiddle

Borrowing heavily from jSang's answer and I'd do it like this:

$(document).ready(function(){
    //assuming the validation fires on the click of a button
    $("#btnSubmit").click(function(){
        var haveEmpty = false;
        var blnIsValid = true;
        $(":text[class^='number']").each(function(i){
            if( $(this).val() != "" )
            {
                if( haveEmpty )
                {
                   blnIsValid = false;
                   //need to do something to let the user know validation failed here
                }
            }
            else
                haveEmpty = true;
        });
        return blnIsValid;
    });
});