更有效地编写这个javascript的方法

Question

I am creating a contact form for my website and and using javascript to the first layer of validation before submitting it which is then checked again via php but i am relatively new to javascript, here is my script...

$("#send").click(function() {
    var fullname = $("input#fullname").val();
    var email = $("input#email").val();
    var subject = $("input#subject").val();
    var message = $("textarea#message").val();
    if (fullname == ""){
        $("input#fullname").css("background","#d02624");
        $("input#fullname").css("color","#121212");
    }else{
        $("input#fullname").css("background","#121212");
        $("input#fullname").css("color","#5c5c5c");
    }
    if (email == ""){
        $("input#email").css("background","#d02624");
        $("input#email").css("color","#121212");
    }else{
        $("input#email").css("background","#121212");
        $("input#email").css("color","#5c5c5c");
    }
    if (subject == ""){
        $("input#subject").css("background","#d02624");
        $("input#subject").css("color","#121212");
    }else{
        $("input#subject").css("background","#121212");
        $("input#subject").css("color","#5c5c5c");
    }
    if (message == ""){
        $("textarea#message").css("background","#d02624");
        $("textarea#message").css("color","#121212");
    }else{
        $("textarea#message").css("background","#121212");
        $("textarea#message").css("color","#5c5c5c");
    }
    if (name && email && subject && message != ""){
        alert("YAY");
    }
});

How can i write this more efficiently and make the alert show if all the fields are filled out, thanks.

Answer 1

$("#send").click(function() {
    var failed = false;

    $('input#fullname, input#email, input#subject, textarea#message').each(function() {
        var item = $(this);
        if (item.val()) {
            item.css("background","#121212").css("color","#5c5c5c");
        } else {
            item.css("background","#d02624").css("color","#121212");
            failed = true;
        }
    });

    if (failed){
        alert("YAY");
    }
});

Answer 2

glavic and matt's answers were exactly what I was going to suggest, except I would take it a step further by separating the logic from the presentation.

Have classes defined in your css for when a field contains an invalid entry, and add or remove that class using $.addClass() or $.removeClass()

Answer 3

Since you're using jQuery, I would recommend setting a class on each field that requires a non-blank value (class="required").

Then you do something like this:

var foundEmpty = false;
$(".required").each(function()
{
   if($(this).val())
   {
       foundEmpty=true;
       $(this).style("background-color", "red");
   }
});
if(foundEmpty)
{
  alert("One or more fields require a value.");
}

Answer 4

Giving them a common class, define classes to apply the styles, and do this:

JS

$("#send").click(function() {
    $('.validate').attr("class", function() {
        return $(this).val() === "" ? "validate invalid" : "validate valid";
    });
    if( $('.invalid').length === 0 ) {
        alert('YAY');
    }
});

CSS

.valid {
    background:#121212;
    color:#5c5c5c
}

.invalid {
    background:#d02624;
    color:#121212;
}

HTML

<button id="send">SEND</button><br>
<input class="validate"><br>
<input class="validate"><br>
<input class="validate"><br>
<input class="validate">

---

JSFIDDLE DEMO

---

A little bit more efficient approach:

var validate = $('.validate');

$("#send").click(function() {
    validate.attr("class", function() {
        return $(this).val() === "" ? "validate invalid" : "validate valid";
    });
    if( validate.filter('.invalid').length === 0 ) {
        alert('YAY');
    }
});

Answer 5

You can use jQuery to iterate over each object and get their values. Depending on your form, this code will change, but it's to give you an example. I'm probably missing a couple of brackets here and there but the concept is there.

var objectName=$(this).attr('id');    
$('#formId').children().each(
        function(){

            if ($(this).value == ""){
                 $(this).css("background","#d02624");
                 $(this).css("color","#121212");
                 $error[objectName]='true';

            }else{
                 $(this).css("background","#121212");
                 $(this).css("color","#5c5c5c");
                 $error[objectName]='false';
            }




        }
    );
           $.each(error, function(key, value){


                if (value=='false'){
                  alert (key + 'is empty');
                }
           });

Answer 6

I would probably divide part of this up into my css file. If any of the fields are empty add a class like "empty" to the object, if not, remove it. Then in your css file you can add some descriptors like:

input#fullname,
input#email {
   ...
}

input#fullname.empty,
input#email.empty {
    ...
}

You can use jQuery addClass() and removeClass().

You can then add a loop as follows:

var inputs = new Array();
inputs[0] = "input#fullname";
inputs[1] = "input#email";
inputs[2] = "input#subject";
inputs[3] = "textarea#message";
var complete = true;
for (var i = 0; i < 4; i++) {
    var value = $(inputs[0]).val();
    if (value.length > 0) {
        $(inputs[i]).removeClass("empty");
    } else {
        complete = false;
        $(inputs[i]).addClass("empty");
    }
}
if (complete) {
}

EDIT:

There you go, fixed it for you.