How to automatically adjust content fontsize to fi

EDIT: Ok, so I approached the problem the wrong way: to do what I intended to, I just needed to check if there was an overflow.

Here is the code (if it can help anyone):

<script type="text/javascript">
 function textfit(){
    var spans = document.body.getElementsByTagName("span");

    for(var i = 0, l = spans.length; i < l; i++){ 
        var span = spans[i];
        var font = window.getComputedStyle(span, null).getPropertyValue('font-size');    
        var fontSize = parseInt(font);

    do {
        span.style.fontSize = (fontSize --) + "px";
    } while (span.scrollHeight > span.clientHeight || span.scrollWidth > span.clientWidth);

    }
}

$(document).ready(function() {
    textfit();
});

</script>

OLD POST:

My problem is simple: I have a HTML page with a lot of span but not all of them have the same content. Regarding that, I want to adapt the fontsize of each content to fit perfectly its span; please note that I don't want to cut the textcontent, or add dots if it's too long, I just want to modify the fontSize.

JS:

function = textfit(){
    var spans = document.body.getElementsByTagName("span");

    for(var i = 0, l = spans.length; i < l; i++){           
        var maxHeight = spans[i].offsetHeight;
        var maxWidth = spans[i].offsetWidth;           
        var textHeight = $(spans[i].textContent).height();
        var textWidth = $(spans[i].textContent).width();
        var fontSize = spans[i].style.fontSize;

        do {
            fontSize = fontSize - 1;
        } while (textHeight > maxHeight || textWidth > maxWidth);

    }
}

$(document).ready(function() {
    textfit();
});

HTML/CSS:

<style>
    span{
        display: inline-block;
        width: 100px;
        height: 100px;
        font-size: 20pt;       
    }
</style>
        ......
<body>
    <div>
        <span>SMALL</span>
        <span>MEEEEEEEEEEEEEDIUM</span>
        <span>HUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUGE</span>
    </div>
</body>

As you may see, I'm using a "for" to run through every span and a "do...while" to adjust the font size of each of them.

My problems:

it looks like I'm not able to get the textcontent size (getting a "null" instead)
same thing with the fontsize (I'm getting an empty string)

Or maybe I'm approaching the problem the wrong way and I need to do it differently...

NB: JS are a little bit "new" for me so sorry if I did rookie mistakes

you are reseting a local variable by fontSize = fontSize - 1;, on a related note, textHeight and textWidth will not be update automatically by changing the fontsize, they are local variables.

On the other hand, you will need to wrap your texts in an additional element to be able to measure its dimensions.

<style>
    .wrapper{
        display: inline-block;
        width: 100px;
        height: 100px;
        font-size: 20pt;       
    }
</style>
        ......
<body>
    <div>
        <span class='wrapper'><span>SMALL</span></span>
        <span class='wrapper'><span>MEEEEEEEEEEEEEDIUM</span></span>
        <span class='wrapper'><span>HUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUGE</span></span>
    </div>
</body>

JS:

function = textfit(){
    var spans = document.body.getElementsByClassName("wrapper");

    for(var i = 0, l = spans.length; i < l; i++){ 
        var span = spans[i];
        var maxHeight = span.offsetHeight;
        var maxWidth = span.offsetWidth;           
        var fontSize = parseInt(span.style.fontSize);

        do {
            var textHeight = span.firstChild.offsetHeight();
            var textWidth = span.firstChild.offsetWidth();
            span.style.fontSize = (fontSize --)+"pt";
        } while (textHeight > maxHeight || textWidth > maxWidth);
        //PS I suggest a binary-search-like algorithm to save time

    }
}

$(document).ready(function() {
    textfit();
});