Javascript function inside php

Question

I try to create a button in php and increase or decrease its value (inside the text input) on click.

<?php

echo "<script>
    function inc(elem)
    {
        x = elem.value;
        //alert('dsadasdasdsadasdas');
        if(x<31)
        {
        x= x+1;
        }
        alert(x);
        elem.value = x;
    }
    </script>";

            echo '<form action="tziros.php" method="post">';
            echo '<input type="text" value="1" name="tziros_imeras">';
            echo '<br>';
            //echo '<input type="button" value="ADD +" onClick="inc(document.getElementById("tziros_imeras"))">';
            echo '<input type="button" value="ADD +" onClick="inc(document.getElementById(\'tziros_imeras\'))">'
            //echo '<input type="button" value="DEC -" onClick="dec();">';  
            echo '<input type="submit" name="submit_tziros_meras" value="OK">';
            echo '</form>'; 
?>

Problem is that javascript is not running at all .

EDIT : after reading your answers i came up with this: js:

 function inc(elem)
        {
        elem.value++;
        }

and on the form:

echo '<input type="text" value="1" id="tziros_imeras" name="tziros_imeras">';

So now at last, the js is running .

Stylistic note: If you output mutliple lines of HTML or Javascript, break out of ?> PHP mode, or use a HEREDOC string. — mario
– mario, Commented Aug 12, 2013 at 18:08

Nir Alfasi · Accepted Answer · 2013-08-12 18:57:54Z

1

You're looking for tziros_imeras by ID (getElementByID) but you have only the name property set up to tziros_imeras
you have only the method inc() - you're missing the method dec()

and most important:

you're incrementing x which is a local variable (it doesn't affect the actual element), you should do instead:

elem.value += 1;

edited Aug 12, 2013 at 18:57

answered Aug 12, 2013 at 18:11

Nir Alfasi

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2 Comments

Βασιλης Ιωσηφιδης Over a year ago

i know it try to fix the inc first

Nir Alfasi Over a year ago

@ΒασιληςΙωσηφιδης check out the last bullet!

please_delete_my_account · Accepted Answer · 2013-08-12 18:08:42Z

0

Update your PHP to use this form so it is easier to read and debug:

echo reference

echo <<<END
content here will be printed
multiple lines!
END;

I'm not sure I believe you, that is is not "running". Insert an alert in your JavaScript to verify.

alert('I am alive');

answered Aug 12, 2013 at 18:08

please_delete_my_account

1199 bronze badges

2 Comments

Igor Dymov Over a year ago

what does it have with the question?

Mark Baker Over a year ago

Nothing directly, but it does make it easier to read (though dropping out of PHP completely would be even easier): so it should be a comment rather than an answer

user1637579 · Accepted Answer · 2013-08-12 18:11:57Z

0

This part of the code:

echo '<input type="button" value="ADD +" onClick="inc(document.getElementById("tziros_imeras"))">';

Needs to be like this:

echo '<input type="button" value="ADD +" onClick="inc(document.getElementById(\'tziros_imeras\'))">';

The JS being outputted was like this:

onClick="inc(document.getElementById("tziros_imeras"))"

Which, as you'll notice, has messed up quotes. This is what was causing the JS to fail to run (look in your browser console and you'll see the errors as well).

As some others have said, you have some JS errors as well, but this is the main issue related to your question.

answered Aug 12, 2013 at 18:11

user1637579

2 Comments

Βασιλης Ιωσηφιδης Over a year ago

i switched the line with the one of yours but still the alerts i have dont run.

user1637579 Over a year ago

Note that I said you still have some JS errors. Your other problem is that you're trying to use document.getElementById, but tziros_imeras is the NAME of the text field.

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