JavaScript/JQuery function doesn't return anything

Question

My function in JavaScript/JQuery doesn't return anything; I want it to return the result for me but it won't. As you can see, the return is the $("#resultado").html("O Valor do produto ficara "+resultado); but this doesn't appear as it should when the function is run:

<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.0/jquery.min.js"></script>
<script type="text/javascript">
     $("#target").submit(function(){

    var preco_dolar = $("#preco_dolar").val(); 
    var dolar = $("#dolar").val();
    var frete = $("#frete").val();


    if ($('#drop').is(':checked'))
    {
    var drop = 5.8;
    }else var drop = 0; 


    if(typeof preco_dolar == "undefined"){
        alert("Erro ! Falta preco do produto");
    }

    if(typeof frete == "undefined"){
        var frete = 40;
    }

    if(typeof dolar == "undefined"){
        var dolar = 2.16;
    }




    var resultado = (preco_dolar*dolar)+frete;

    $("#resultado").html("O Valor do produto ficara "+resultado);




});
</script>

Can someone point out where I'm going wrong please?

metadings · Accepted Answer · 2013-01-23 19:01:11Z

1

First you need to wrap your script into

// here $("#target") is nothing

$(document).ready(function () {
    // here $("target") exists
});

Second for your improvement, don't use

if(typeof dolar == "undefined"){
    dolar = 2.16;
}

Use instead

if(!dolar){
    dolar = 2.16;
}

That is the same as you would do:

if(!dolar && dolar == 0 && dolar == "" && dolar == false && dolar == undefined){
    dolar = 2.16;
}

To make 0 a valid value, use

if (!dolar && dolar !== 0) {
    dolar = 2.16;
}

Also don't use var dolar = 0; twice. If you declared it already, simply use dolar =, to not overwrite the already declared var.

edited Jan 23, 2013 at 19:01

answered Jan 23, 2013 at 18:42

metadings

3,8482 gold badges30 silver badges37 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

epascarello Over a year ago

1. You only have to wrap the script if it appears before the form is rendered on the page. 2. What if dolar is zero? You just reset it! typeof checks are not bad, would probably be better as just if (dolar === undefined) {

metadings Over a year ago

@epascarello yeah you're right because of 0 being a valid value. he actually declares jquery script tag right before his script, so it's predictable the element doesn't exist already.

epascarello Over a year ago

Probably even easier to just do var dolar = $("#dolar").val() || 2.16; As long as val() returns a string. :)

metadings Over a year ago

@epascarello hah expanding your tricks: var dolar = +$("#dolar").val() || 2.16 makes sure you have a number. but we are losing now the valid 0 so an if check will be required.

epascarello · Accepted Answer · 2013-01-23 18:38:55Z

1

You are not calling the form submission so the page is refreshing and resetting the page. Use preventDefault to stop the form submission.

$("#target").submit(function (evt) {
    evt.preventDefault();
    ...

answered Jan 23, 2013 at 18:38

epascarello

208k20 gold badges206 silver badges246 bronze badges

Comments

Nirvana Tikku · Accepted Answer · 2013-01-23 18:40:42Z

1

return false;

should suffice.

alternatively, you could prevent the default behavior by

e.preventDefault();
e.stopPropagation();

answered Jan 23, 2013 at 18:40

Nirvana Tikku

4,2152 gold badges23 silver badges28 bronze badges

Comments

George · Accepted Answer · 2013-01-23 18:39:47Z

0

You don't have a return statement. Javascript functions require a return statement to return a value:

function test() {
    return 5;
}

answered Jan 23, 2013 at 18:39

George

4,27727 silver badges34 bronze badges

1 Comment

epascarello Over a year ago

The question sounds like this is what the OP was referring too, but that is not the case.

Collectives™ on Stack Overflow

JavaScript/JQuery function doesn't return anything

4 Answers 4

4 Comments

Comments

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

4 Comments

Comments

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related