How to alert once in a JavaScript loop

Question

code : In the below code shown, the alert message keeps on looping till the end of the statement.I need a alert statement to alert only once.How to achieve this?

Here it is checking the output of a checkbox if its not selected it shows undefined

 for(j=1;j<=numOflimit;j++)
    {
      var select = $("input[name=select+j]:checked").val();
        //alert (select);
        //$check='undefined';


        if(select==undefined)

        {
            alert ("Please select atleast one product");
        }
        else
        {
            var postData    =   $("form").serialize();//"product_name="+product_name+"&barcode="+barcode+"&Quantity"+Quantity;
            $.ajax
            ({
               type: 'POST',
                url: 'http://localhost/example/index.php/castoutput',                      
                data: postData,
                success: function(html) {
                    // alert(html);
                    $('#cast2').html(html); 
                }
         });
        }
   }

This looks like JavaScript to me, not PHP.

Diodeus - James MacFarlane
– Diodeus - James MacFarlane

2011-08-30 14:27:22 +00:00
Commented Aug 30, 2011 at 14:27 — Diodeus - James MacFarlane
– Diodeus - James MacFarlane, Commented Aug 30, 2011 at 14:27

user909462 · Accepted Answer · 2011-08-30 14:28:21Z

6

You could make a variable which is either true or false, if the alert has been triggered once put it on false & check with an if, if its true or false.

if (showAlert==true)
{
   alert ("Please select atleast one product");
   showAlert = false;
}

answered Aug 30, 2011 at 14:28

user909462

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Comments

cwallenpoole · Accepted Answer · 2011-08-30 14:29:17Z

2

You're using a string instead of a concatenation here:

$("input[name=select+j]:checked").val();

You need to place j outside of the quotes:

$("input[name=select"+j+"]:checked").val();

Otherwise it is always undefined.

Just curious, by the way, why do you need to loop here anyway?

answered Aug 30, 2011 at 14:29

cwallenpoole

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1 Comment

user876200 Over a year ago

in order to check whether the checkbox is selected or not... its not working ... i tried your method

Rick · Accepted Answer · 2011-08-30 19:25:39Z

2

There is absolutely no reason what-so-ever to loop over input elements to determine if any of them are checked. Since you're already using the :checked selector, simply check the length of the matched set of elements - it's very simple:

var $checked = $("input[type='checkbox']:checked");

// If none of the checkboxes are checked, alert to the user
if ( !$checked.length ) {

    alert("Please select atleast one product");

} else {

    // do ajax post stuff here.

}

answered Aug 30, 2011 at 19:25

Rick

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Comments

Sergey Volosevich · Accepted Answer · 2011-08-30 14:29:02Z

0

try this

if(typeof(select)=='undefined')

and if you will need to alert once - use yours j counter

if (j==1) {alert('')}

answered Aug 30, 2011 at 14:29

Sergey Volosevich

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Comments

Some Guy · Accepted Answer · 2011-08-30 14:48:34Z

0

As far as I can tell, you don't want to do the else statement either, so there's no use of letting the for loop run. Simply use:

if(select==undefined)
        {
            alert ("Please select atleast one product");
            j = numOflimit+1;
        }

answered Aug 30, 2011 at 14:48

Some Guy

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Comments

Roger · Accepted Answer · 2011-08-30 14:54:30Z

0

did you try just having it exit the for loop to another function that throws an error if it equals undefined since it looks like your just trying to submit the form. So just make it exit on undefined to a function that throws an alert saying whatever you like.

answered Aug 30, 2011 at 14:54

Roger

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