¿Por qué no funciona este Javascript? Cambio de estilo

I cant for the life of me figure out why this doesn't work:

javascript:

//==================================//
// resize_middle                            //
//----------------------------------//
// Resizes the content and left     //
// navigation div to make up the        //
// remains of available space.      //
//==================================//
function resize_middle()
{
    min_height = (window.innerHeight - 276) + "px";
    middle_left = document.getElementById("middle_left");
    middle_right = document.getElementById("middle_right");
    alert("its not going to work!");
    alert("here goes...");
    alert(min_height);
    middle_left.style.minHeight = min_height;
    alert("it works!");
    middle_right.style.minHeight = min_height;
}
//==================================//
// event handlers                           //
//==================================//
window.onload = resize_middle();
window.onresize = resize_middle();

html(body & javascript bit in head shown only):

<script src="javascript.js" type="text/javascript" charset="utf-8"></script>
<body>
    <div id="container">
        <div id="central_column">
            <div id="top_left">
                <img src="./images/icon.png" alt="icon" style="width:100%;height:auto;" />
            </div>
            <div id="top_right">
                top right
            </div>
            <div id="middle_left">
                middle left
            </div>
            <div id="middle_right">
                middle right
            </div>
            <div id="bottom">
                bottom
            </div>
        </div>
    </div>
</body>

I'v used this before and have a working copy of some only slightly different code, but it works perfectly. I get the debugging alerts up until "it works!", which I don't get. Thanks in advance, ell.

preguntado el 08 de enero de 11 a las 19:01

/* free-form comments\nvery useful they are */ -

I fuertemente recommend using a proper debugger for JavaScript, like Firebug for Firefox. -

3 Respuestas

You need this instead:

window.onload = resize_middle;
window.onresize = resize_middle;

Because as having it resize_middle() the function is processed immediately and the result is added to the event. You want the function itself to be added to the event so you leave off the () unless your function returns a function for the event to use.

Respondido el 08 de enero de 11 a las 22:01

Catches everyone out at least once - Kurru

You need this instead:

window.onload = resize_middle;
window.onresize = resize_middle;

Currently you're llamar those functions and assigning their return value to the event. What you want is to assign the functions sí mismos to the events, and let the events call them.


Nota al margen:

Unless the variables in resize_middle are defined elsewhere and you intend for them to be accessible to the outer scope, it is good practice to use the var keyword when defining new variables.

function resize_middle()
{
      // Changed to use "var"
    var min_height = (window.innerHeight - 276) + "px";
    var middle_left = document.getElementById("middle_left");
    var middle_right = document.getElementById("middle_right");

    alert("its not going to work!");
    alert("here goes...");
    alert(min_height);
    middle_left.style.minHeight = min_height;
    alert("it works!");
    middle_right.style.minHeight = min_height;
}

Respondido el 08 de enero de 11 a las 22:01

window.onload = resize_middle;

Read this resource on assigning event handlers.

Respondido el 08 de enero de 11 a las 22:01

Oh you are joking me! I can't beleive this! Why does this work? - Ana

@Ell: because resize_middle evalúa a la función, resize_middle() evalúa a the value returned by the function. - Matt Ball

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