jQuery.each（values，function（i，v）{…}）为什么v未定义？

Question

I have several textboxes which I need to check before post them back. I do this with jQuery using each function. When the submit button is pressed (LinkButton1) I iterate over the textboxes and check they values:

<asp:textbox id="txt1" class="tocheck" runat="server />
<asp:textbox id="txt2" class="tocheck" runat="server />
<asp:textbox id="txt3" class="tocheck" runat="server />

$('#LinkButton1').click(function () {
    var error = false;
    $.each('.tocheck', function (i, v) {
        checkVal(v.val());
    });
});

But a runtime error is thrown saying v is undefined:

How can I retrieve the textbox value?

Thank you.

Answer 1

You don't need to pass in v - remove it.

And use $(this) instead.

IE

$('#LinkButton1').click(function () {
    var error = false;
    $('.tocheck').each( function () {
        checkVal($(this).val());
    });
});

Answer 2

The issue is that you aren't passing in a collection correctly.

$('#LinkButton1').click(function () {
    var error = false;
    $.each('.text', function (i, v) { // <-- you are passing in a STRING not a collection of elements
        checkVal(v.val());
    });
});

try

$('#LinkButton1').click(function () {
    var error = false;
    $.each($('.text'), function (i, v) {
        checkVal($(v).val());// <-- need to wrap in jQuery to use jQuery methods
    });
});

Answer 3

you got a error in the class selector. change it to

$(".tocheck").each(function(i, v){
    checkVal($(v).val());
})

Answer 4

Firstly

$.each('.tocheck', function (i, v) {
        checkVal(v.val());
    });

supposed to be either

$('.tocheck').each(function (i, v) {
        checkVal(v.value);
});

' OR /

 $.each( $('.tocheck'), function (i, v) {
            checkVal(v.value);
        });

Secondly v here is the DOM object and you are trying to use jQuery method on it .. That's the reason for the error..

So v.val()

supposed to be

v.value OR $(v).val(); OR this.value OR $(this).val();

Answer 5

The $.each function designed for mostly value arrays like intergers or string that s why v is value not item. so you should use each jQuery array as below.

$(".tocheck").each(function (index, item)
{
   alert($(item).val());
});

Answer 6

$('.tocheck').each( function () {
        checkVal($(this).val());
    });