How do I return true from a javascript function along with a value?

Question

Hello guys i am using a function to detect the image extension.

<body>
<input id="imgExtension" type="text" />
<input id="myFile" type="file" />
<script>
function checkExt(x){
var y = x.split('.').pop();
if (y != "jpg" && y != "png") {
    return false;
}

else {
    // i want to return *y*[image extension] from here
    return true;
}
}

$(function(){
$("#myFile").change(function(){
var x = $(this).val;
    if(checkExt(x)){
       // i want to put [image extension] here in #imgExtension
       $('#imgExtension').val();
    }

    else  {
       alert("Error, invalid image extension");
    }
}    
}
</script>
</body>

Recently, I was just checking the image extension and returning true or false but i want to get the extension as well because I need to parse it to my PHP script.

you could just return an object : return {valid: true, extension : y} — Peter Fischaleck
– Peter Fischaleck, Commented May 4, 2015 at 9:00

Diogo Cunha · Accepted Answer · 2015-05-04 09:00:27Z

5

Instead of return true or false you can return just the extension or null if there is no extension at all.

In other hand you can create one js object that contains the two values, but i would go for the first.

answered May 4, 2015 at 9:00

Diogo Cunha

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3 Comments

user4853991 Over a year ago

as u said return null/extension. Can i put it as returning false/extension ??

Diogo Cunha Over a year ago

why do you want to return 2 completely different types? that is not a good practice, you can easily check if a value is null so it as better effect than just return true/false. If you want to have a well structured code returning just the extension/null is a better approach, but you can always return a object

user4853991 Over a year ago

how to work with the returned obeject, how to use it in if,else conditions ?

Robin · Accepted Answer · 2015-05-04 09:00:46Z

2

The easiest way to return more than one value is to return an object.

return { value: true, extension: '.jpg' };

You can then access the value returned as a normal object.

answered May 4, 2015 at 9:00

Robin

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3 Comments

Frnak Over a year ago

i don't think this is what he needs - he wants to return true so his check is correct

user4853991 Over a year ago

and how wud i verify then ? if(checkExt(x).value == false){ return false; } else{ $('#imgExtension').val(checkExt(x).extension); }

Robin Over a year ago

You could do so. A more common way to do it would be to save the response to a variable. var extCheck = checkExt(x); and then access it with if (extCheck.value) to see if it was true and extCheck.extension to access the extension.

saml · Accepted Answer · 2015-05-04 09:02:45Z

0

You cannot return two things (unless you use an array). I suggest that you return either the extension or null. Because of something called falsfy in JavaScript, calling if(checkExt(x)) will evalulate to false for null and true for jpg or png.

answered May 4, 2015 at 9:02

saml

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Comments

Kevin Kuyl · Accepted Answer · 2015-05-04 09:07:15Z

0

You dont need to return 2 values. checkExt works as it should if you just return the value, or nothing at all. The cleanest way to do things like this is with a ternary statement (google it, easy to learn, will save hours of your life)

function checkExt(x){
  var y = x.split('.').pop();
  return y != "jpg" && y != "png" ? false : y;
}

answered May 4, 2015 at 9:07

Kevin Kuyl

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