I need to display user entered text into a fixed size div. What i want is for the font size to be automatically adjusted so that the text fills the box as much as possible.

So - If the div is 400px x 300px. If someone enters ABC then it's really big font. If they enter a paragraph, then it would be a tiny font.

I'd probably want to start with a maximum font size - maybe 32px, and while the text is too big to fit the container, shrink the font size until it fits.

Solution 1

Thanks Attack. I wanted to use jQuery.

You pointed me in the right direction, and this is what I ended up with:

Here is a link to the plugin: https://plugins.jquery.com/textfill/
And a link to the source: http://jquery-textfill.github.io/

;(function($) {
    $.fn.textfill = function(options) {
        var fontSize = options.maxFontPixels;
        var ourText = $('span:visible:first', this);
        var maxHeight = $(this).height();
        var maxWidth = $(this).width();
        var textHeight;
        var textWidth;
        do {
            ourText.css('font-size', fontSize);
            textHeight = ourText.height();
            textWidth = ourText.width();
            fontSize = fontSize - 1;
        } while ((textHeight > maxHeight || textWidth > maxWidth) && fontSize > 3);
        return this;
    }
})(jQuery);

$(document).ready(function() {
    $('.jtextfill').textfill({ maxFontPixels: 36 });
});

and my html is like this

<div class='jtextfill' style='width:100px;height:50px;'>
    <span>My Text Here</span>
</div>

This is my first jquery plugin, so it's probably not as good as it should be. Pointers are certainly welcome.

Solution 2

I didn't find any of the previous solutions to be adequate enough due to bad performance, so I made my own that uses simple math instead of looping. Should work fine in all browsers as well.

According to this performance test case it is much faster then the other solutions found here.

(function($) {
    $.fn.textfill = function(maxFontSize) {
        maxFontSize = parseInt(maxFontSize, 10);
        return this.each(function(){
            var ourText = $("span", this),
                parent = ourText.parent(),
                maxHeight = parent.height(),
                maxWidth = parent.width(),
                fontSize = parseInt(ourText.css("fontSize"), 10),
                multiplier = maxWidth/ourText.width(),
                newSize = (fontSize*(multiplier-0.1));
            ourText.css(
                "fontSize", 
                (maxFontSize > 0 && newSize > maxFontSize) ? 
                    maxFontSize : 
                    newSize
            );
        });
    };
})(jQuery);

If you want to contribute I've added this to Gist.

Solution 3

As much as I love the occasional upvotes I get for this answer (thanks!), this is really not the greatest approach to this problem. Please check out some of the other wonderful answers here, especially the ones that have found solutions without looping.


Still, for the sake of reference, here's my original answer:

<html>
<head>
<style type="text/css">
    #dynamicDiv
    {
    background: #CCCCCC;
    width: 300px;
    height: 100px;
    font-size: 64px;
    overflow: hidden;
    }
</style>

<script type="text/javascript">
    function shrink()
    {
        var textSpan = document.getElementById("dynamicSpan");
        var textDiv = document.getElementById("dynamicDiv");

        textSpan.style.fontSize = 64;

        while(textSpan.offsetHeight > textDiv.offsetHeight)
        {
            textSpan.style.fontSize = parseInt(textSpan.style.fontSize) - 1;
        }
    }
</script>

</head>
<body onload="shrink()">
    <div id="dynamicDiv"><span id="dynamicSpan">DYNAMIC FONT</span></div>
</body>
</html>

And here's a version with classes:

<html>
<head>
<style type="text/css">
.dynamicDiv
{
    background: #CCCCCC;
    width: 300px;
    height: 100px;
    font-size: 64px;
    overflow: hidden;
}
</style>

<script type="text/javascript">
    function shrink()
    {
        var textDivs = document.getElementsByClassName("dynamicDiv");
        var textDivsLength = textDivs.length;

        // Loop through all of the dynamic divs on the page
        for(var i=0; i<textDivsLength; i++) {

            var textDiv = textDivs[i];

            // Loop through all of the dynamic spans within the div
            var textSpan = textDiv.getElementsByClassName("dynamicSpan")[0];

            // Use the same looping logic as before
            textSpan.style.fontSize = 64;

            while(textSpan.offsetHeight > textDiv.offsetHeight)
            {
                textSpan.style.fontSize = parseInt(textSpan.style.fontSize) - 1;
            }

        }

    }
</script>

</head>
<body onload="shrink()">
    <div class="dynamicDiv"><span class="dynamicSpan">DYNAMIC FONT</span></div>
    <div class="dynamicDiv"><span class="dynamicSpan">ANOTHER DYNAMIC FONT</span></div>
    <div class="dynamicDiv"><span class="dynamicSpan">AND YET ANOTHER DYNAMIC FONT</span></div>
</body>
</html>

Solution 4

Most of the other answers use a loop to reduce the font-size until it fits on the div, this is VERY slow since the page needs to re-render the element each time the font changes size. I eventually had to write my own algorithm to make it perform in a way that allowed me to update its contents periodically without freezing the user browser. I added some other functionality (rotating text, adding padding) and packaged it as a jQuery plugin, you can get it at:

https://github.com/DanielHoffmann/jquery-bigtext

simply call

$("#text").bigText();

and it will fit nicely on your container.

See it in action here:

http://danielhoffmann.github.io/jquery-bigtext/

For now it has some limitations, the div must have a fixed height and width and it does not support wrapping text into multiple lines.

I will work on getting an option to set the maximum font-size.

Edit: I have found some more problems with the plugin, it does not handle other box-model besides the standard one and the div can't have margins or borders. I will work on it.

Edit2: I have now fixed those problems and limitations and added more options. You can set maximum font-size and you can also choose to limit the font-size using either width, height or both. I will work into accepting a max-width and max-height values in the wrapper element.

Edit3: I have updated the plugin to version 1.2.0. Major cleanup on the code and new options (verticalAlign, horizontalAlign, textAlign) and support for inner elements inside the span tag (like line-breaks or font-awesome icons.)

Solution 5

This is based on what GeekyMonkey posted above, with some modifications.

; (function($) {
/**
* Resize inner element to fit the outer element
* @author Some modifications by Sandstrom
* @author Code based on earlier works by Russ Painter (WebDesign@GeekyMonkey.com)
* @version 0.2
*/
$.fn.textfill = function(options) {

    options = jQuery.extend({
        maxFontSize: null,
        minFontSize: 8,
        step: 1
    }, options);

    return this.each(function() {

        var innerElements = $(this).children(':visible'),
            fontSize = options.maxFontSize || innerElements.css("font-size"), // use current font-size by default
            maxHeight = $(this).height(),
            maxWidth = $(this).width(),
            innerHeight,
            innerWidth;

        do {

            innerElements.css('font-size', fontSize);

            // use the combined height of all children, eg. multiple <p> elements.
            innerHeight = $.map(innerElements, function(e) {
                return $(e).outerHeight();
            }).reduce(function(p, c) {
                return p + c;
            }, 0);

            innerWidth = innerElements.outerWidth(); // assumes that all inner elements have the same width
            fontSize = fontSize - options.step;

        } while ((innerHeight > maxHeight || innerWidth > maxWidth) && fontSize > options.minFontSize);

    });

};

})(jQuery);

Solution 6

Here's an improved looping method that uses binary search to find the largest possible size that fits into the parent in the fewest steps possible (this is faster and more accurate than stepping by a fixed font size). The code is also optimized in several ways for performance.

By default, 10 binary search steps will be performed, which will get within 0.1% of the optimal size. You could instead set numIter to some value N to get within 1/2^N of the optimal size.

Call it with a CSS selector, e.g.: fitToParent('.title-span');

/**
 * Fit all elements matching a given CSS selector to their parent elements'
 * width and height, by adjusting the font-size attribute to be as large as
 * possible. Uses binary search.
 */
var fitToParent = function(selector) {
    var numIter = 10;  // Number of binary search iterations
    var regexp = /\d+(\.\d+)?/;
    var fontSize = function(elem) {
        var match = elem.css('font-size').match(regexp);
        var size = match == null ? 16 : parseFloat(match[0]);
        return isNaN(size) ? 16 : size;
    }
    $(selector).each(function() {
        var elem = $(this);
        var parentWidth = elem.parent().width();
        var parentHeight = elem.parent().height();
        if (elem.width() > parentWidth || elem.height() > parentHeight) {
            var maxSize = fontSize(elem), minSize = 0.1;
            for (var i = 0; i < numIter; i++) {
                var currSize = (minSize + maxSize) / 2;
                elem.css('font-size', currSize);
                if (elem.width() > parentWidth || elem.height() > parentHeight) {
                    maxSize = currSize;
                } else {
                    minSize = currSize;
                }
            }
            elem.css('font-size', minSize);
        }
    });
};

Solution 7

I've created a directive for AngularJS - heavely inspired by GeekyMonkey's answer but without the jQuery dependency.

Demo: http://plnkr.co/edit/8tPCZIjvO3VSApSeTtYr?p=preview

Markup

<div class="fittext" max-font-size="50" text="Your text goes here..."></div>

Directive

app.directive('fittext', function() {

  return {
    scope: {
      minFontSize: '@',
      maxFontSize: '@',
      text: '='
    },
    restrict: 'C',
    transclude: true,
    template: '<div ng-transclude class="textContainer" ng-bind="text"></div>',
    controller: function($scope, $element, $attrs) {
      var fontSize = $scope.maxFontSize || 50;
      var minFontSize = $scope.minFontSize || 8;

      // text container
      var textContainer = $element[0].querySelector('.textContainer');

      angular.element(textContainer).css('word-wrap', 'break-word');

      // max dimensions for text container
      var maxHeight = $element[0].offsetHeight;
      var maxWidth = $element[0].offsetWidth;

      var textContainerHeight;
      var textContainerWidth;      

      var resizeText = function(){
        do {
          // set new font size and determine resulting dimensions
          textContainer.style.fontSize = fontSize + 'px';
          textContainerHeight = textContainer.offsetHeight;
          textContainerWidth = textContainer.offsetWidth;

          // shrink font size
          var ratioHeight = Math.floor(textContainerHeight / maxHeight);
          var ratioWidth = Math.floor(textContainerWidth / maxWidth);
          var shrinkFactor = ratioHeight > ratioWidth ? ratioHeight : ratioWidth;
          fontSize -= shrinkFactor;

        } while ((textContainerHeight > maxHeight || textContainerWidth > maxWidth) && fontSize > minFontSize);        
      };

      // watch for changes to text
      $scope.$watch('text', function(newText, oldText){
        if(newText === undefined) return;

        // text was deleted
        if(oldText !== undefined && newText.length < oldText.length){
          fontSize = $scope.maxFontSize;
        }
        resizeText();
      });
    }
  };
});

Solution 8

I forked the script above from Marcus Ekwall: https://gist.github.com/3945316 and tweaked it to my preferences, it now fires when the window is resized, so that the child always fits its container. I've pasted the script below for reference.

(function($) {
    $.fn.textfill = function(maxFontSize) {
        maxFontSize = parseInt(maxFontSize, 10);
        return this.each(function(){
            var ourText = $("span", this);
            function resizefont(){
                var parent = ourText.parent(),
                maxHeight = parent.height(),
                maxWidth = parent.width(),
                fontSize = parseInt(ourText.css("fontSize"), 10),
                multiplier = maxWidth/ourText.width(),
                newSize = (fontSize*(multiplier));
                ourText.css("fontSize", maxFontSize > 0 && newSize > maxFontSize ? maxFontSize : newSize );
            }
            $(window).resize(function(){
                resizefont();
            });
            resizefont();
        });
    };
})(jQuery);

Solution 9

Here's my modification of the OP's answer.

In short, many people who tried to optimize this complained that a loop was being used. Yes, while loops can be slow, other approaches can be inaccurate.

Therefore, my approach uses Binary Search to find the best Font Size:

$.fn.textfill = function()
{
    var self = $(this);
    var parent = self.parent();

    var attr = self.attr('max-font-size');
    var maxFontSize = parseInt(attr, 10);
    var unit = attr.replace(maxFontSize, "");

    var minFontSize = parseInt(self.attr('min-font-size').replace(unit, ""));
    var fontSize = (maxFontSize + minFontSize) / 2;

    var maxHeight = parent.height();
    var maxWidth = parent.width();

    var textHeight;
    var textWidth;

    do
    {
        self.css('font-size', fontSize + unit);

        textHeight = self.height();
        textWidth = self.width();

        if(textHeight > maxHeight || textWidth > maxWidth)
        {
            maxFontSize = fontSize;
            fontSize = Math.floor((fontSize + minFontSize) / 2);
        }
        else if(textHeight < maxHeight || textWidth < maxWidth)
        {
            minFontSize = fontSize;
            fontSize = Math.floor((fontSize + maxFontSize) / 2);
        }
        else
            break;

    }
    while(maxFontSize - minFontSize > 1 && maxFontSize > minFontSize);

    self.css('font-size', fontSize + unit);

    return this;
}

function resizeText()
{
  $(".textfill").textfill();
}

$(document).ready(resizeText);
$(window).resize(resizeText);

This also allows the element to specify the minimum and maximum font:

<div class="container">
    <div class="textfill" min-font-size="10px" max-font-size="72px">
        Text that will fill the container, to the best of its abilities, and it will <i>never</i> have overflow.
    </div>
</div>

Furthermore, this algorithm is unitless. You may specify em, rem, %, etc. and it will use that for its final result.

Here's the Fiddle: https://jsfiddle.net/fkhqhnqe/1/

Solution 10

I had exactly the same problem with my website. I have a page that is displayed on a projector, on walls, big screens..

As I don't know the max size of my font, I re-used the plugin above of @GeekMonkey but incrementing the fontsize :

$.fn.textfill = function(options) {
        var defaults = { innerTag: 'span', padding: '10' };
        var Opts = jQuery.extend(defaults, options);

        return this.each(function() {
            var ourText = $(Opts.innerTag + ':visible:first', this);
            var fontSize = parseFloat(ourText.css('font-size'),10);
            var doNotTrepass = $(this).height()-2*Opts.padding ;
            var textHeight;

            do {
                ourText.css('font-size', fontSize);
                textHeight = ourText.height();
                fontSize = fontSize + 2;
            } while (textHeight < doNotTrepass );
        });
    };

Solution 11

Here is a version of the accepted answer which can also take a minFontSize parameter.

(function($) {
    /**
    * Resizes an inner element's font so that the inner element completely fills the outer element.
    * @author Russ Painter WebDesign@GeekyMonkey.com
    * @author Blake Robertson 
    * @version 0.2 -- Modified it so a min font parameter can be specified.
    *    
    * @param {Object} Options which are maxFontPixels (default=40), innerTag (default='span')
    * @return All outer elements processed
    * @example <div class='mybigdiv filltext'><span>My Text To Resize</span></div>
    */
    $.fn.textfill = function(options) {
        var defaults = {
            maxFontPixels: 40,
            minFontPixels: 10,
            innerTag: 'span'
        };
        var Opts = jQuery.extend(defaults, options);
        return this.each(function() {
            var fontSize = Opts.maxFontPixels;
            var ourText = $(Opts.innerTag + ':visible:first', this);
            var maxHeight = $(this).height();
            var maxWidth = $(this).width();
            var textHeight;
            var textWidth;
            do {
                ourText.css('font-size', fontSize);
                textHeight = ourText.height();
                textWidth = ourText.width();
                fontSize = fontSize - 1;
            } while ((textHeight > maxHeight || textWidth > maxWidth) && fontSize > Opts.minFontPixels);
        });
    };
})(jQuery);

Solution 12

You can use FitText.js (github page) to solve this problem. Is really small and efficient compared to TextFill. TextFill uses an expensive while loop and FitText don't.

Also FitText is more flexible (I use it in a proyect with very special requirements and works like a champ!).

HTML:

<div class="container">
  <h1 id="responsive_headline">Your fancy title</h1>
</div>

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script src="jquery.fittext.js"></script>
<script>
  jQuery("#responsive_headline").fitText();
</script>

You also can set options to it:

<script>
  jQuery("#responsive_headline").fitText(1, { minFontSize: '30px', maxFontSize: '90px'});
</script>

CSS:

#responsive_headline {
   width: 100%;
   display: block;
}

And if you need it, FitText also has a no-jQuery version.

Solution 13

EDIT: This code was used to show notes on top of a HTML5 video. It changes the font-size on the fly when the video is resized (when the browser window is resized.) The notes was connected to the video (just like notes on YouTube), which is why the code uses instances instead of a DOM handle directly.

As per request I'll throw in some code that I used to achieve this. (Text boxes over an HTML5 video.) The code was written a long time ago, and I quite frankly think it's pretty messy. Since the question is already answered and an answer is already accepted a long time ago I don't bother rewriting this. But if anyone wants to simplify this a bit, you're more than welcome!

// Figure out the text size:
var text = val['text'];
var letters = text.length;
var findMultiplier = function(x) { // g(x)
    /* By analysing some functions with regression, the resulting function that
     gives the best font size with respect to the number of letters and the size
     of the note is:
     g(x) = 8.3 - 2.75x^0.15 [1 < x < 255]
     f(x) = g(letters) * (x / 1000)^0.5
     Font size = f(size)
     */
    return 8.3 - 2.75 * Math.pow(x, 0.15);
};

var findFontSize = function(x) { // f(x)
    return findMultiplier(letters) * Math.pow(x / 1000, 0.5);
};

val.setFontSizeListener = function() {
    p.style.fontSize = '1px'; // So the text should not overflow the box when measuring.
    var noteStyle = window.getComputedStyle(table);
    var width = noteStyle.getPropertyValue('width');
    var height = noteStyle.getPropertyValue('height');
    var size = width.substring(0, width.length - 2) * height.substring(0, height.length - 2);
    p.style.fontSize = findFontSize(size) + 'px';
};
window.addEventListener('resize', val.setFontSizeListener);

You'll probably need to tweak these numbers from font-family to font-family. A good way to do this is download a free graph visualizer called GeoGebra. Change the length of the text and the size of the box. Then you manually set the size. Plot the manual results into the coordinate system. Then you enter the two equations I've posted here and you tweak the numbers until "my" graph fits your own manually plotted points.

Solution 14

The proposed iterative solutions can be sped up dramatically on two fronts:

1) Multiply the font size by some constant, rather than adding or subtracting 1.

2) First, zero in using a course constant, say, double the size each loop. Then, with a rough idea of where to start, do the same thing with a finer adjustment, say, multiply by 1.1. While the perfectionist might want the exact integer pixel size of the ideal font, most observers don't notice the difference between 100 and 110 pixels. If you are a perfectionist, then repeat a third time with an even finer adjustment.

Rather than writing a specific routine or plug-in that answers the exact question, I just rely on the basic ideas and write variations of the code to handle all kinds of layout issues, not just text, including fitting divs, spans, images,... by width, height, area,... within a container, matching another element....

Here's an example:

  var                           nWindowH_px             = jQuery(window).height();
  var                           nWas                    = 0;
  var                           nTry                    = 5;

  do{
   nWas = nTry;
   nTry *= 2;
   jQuery('#divTitle').css('font-size' ,nTry +'px');
  }while( jQuery('#divTitle').height() < nWindowH_px );

  nTry = nWas;

  do{
   nWas = nTry;
   nTry = Math.floor( nTry * 1.1 );
   jQuery('#divTitle').css('font-size' ,nTry +'px');
  }while( nWas != nTry   &&   jQuery('#divTitle').height() < nWindowH_px );

  jQuery('#divTitle').css('font-size' ,nWas +'px');

Solution 15

Just wanted to add my version for contenteditables.

$.fn.fitInText = function() {
  this.each(function() {

    let textbox = $(this);
    let textboxNode = this;

    let mutationCallback = function(mutationsList, observer) {
      if (observer) {
        observer.disconnect();
      }
      textbox.css('font-size', 0);
      let desiredHeight = textbox.css('height');
      for (i = 12; i < 50; i++) {
        textbox.css('font-size', i);
        if (textbox.css('height') > desiredHeight) {
          textbox.css('font-size', i - 1);
          break;
        }
      }

      var config = {
        attributes: true,
        childList: true,
        subtree: true,
        characterData: true
      };
      let newobserver = new MutationObserver(mutationCallback);
      newobserver.observe(textboxNode, config);

    };

    mutationCallback();

  });
}

$('#inner').fitInText();
#outer {
  display: table;
  width: 100%;
}

#inner {
  border: 1px solid black;
  height: 170px;
  text-align: center;
  display: table-cell;
  vertical-align: middle;
  word-break: break-all;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="outer">
  <div id="inner" contenteditable=true>
    TEST
  </div>
</div>

Solution 16

This is the most elegant solution I have created. It uses binary search, doing 10 iterations. The naive way was to do a while loop and increase the font size by 1 until the element started to overflow. You can determine when an element begins to overflow using element.offsetHeight and element.scrollHeight. If scrollHeight is bigger than offsetHeight, you have a font size that is too big.

Binary search is a much better algorithm for this. It also is limited by the number of iterations you want to perform. Simply call flexFont and insert the div id and it will adjust the font size between 8px and 96px.

I have spent some time researching this topic and trying different libraries, but ultimately I think this is the easiest and most straightforward solution that will actually work.

Note if you want you can change to use offsetWidth and scrollWidth, or add both to this function.

// Set the font size using overflow property and div height
function flexFont(divId) {
    var content = document.getElementById(divId);
    content.style.fontSize = determineMaxFontSize(content, 8, 96, 10, 0) + "px";
};

// Use binary search to determine font size
function determineMaxFontSize(content, min, max, iterations, lastSizeNotTooBig) {
    if (iterations === 0) {
        return lastSizeNotTooBig;
    }
    var obj = fontSizeTooBig(content, min, lastSizeNotTooBig);

    // if `min` too big {....min.....max.....}
    // search between (avg(min, lastSizeTooSmall)), min)
    // if `min` too small, search between (avg(min,max), max)
    // keep track of iterations, and the last font size that was not too big
    if (obj.tooBig) {
        (lastSizeTooSmall === -1) ?
            determineMaxFontSize(content, min / 2, min, iterations - 1, obj.lastSizeNotTooBig, lastSizeTooSmall) :
                determineMaxFontSize(content, (min + lastSizeTooSmall) / 2, min, iterations - 1, obj.lastSizeNotTooBig, lastSizeTooSmall);

    } else {
        determineMaxFontSize(content, (min + max) / 2, max, iterations - 1, obj.lastSizeNotTooBig, min);
    }
}

// determine if fontSize is too big based on scrollHeight and offsetHeight, 
// keep track of last value that did not overflow
function fontSizeTooBig(content, fontSize, lastSizeNotTooBig) {
    content.style.fontSize = fontSize + "px";
    var tooBig = content.scrollHeight > content.offsetHeight;
    return {
        tooBig: tooBig,
        lastSizeNotTooBig: tooBig ? lastSizeNotTooBig : fontSize
    };
}

Solution 17

I got the same problem and the solution is basically use javascript to control font-size. Check this example on codepen:

https://codepen.io/ThePostModernPlatonic/pen/BZKzVR

This is example is only for height, maybe you need to put some if's about the width.

try to resize it

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Documento sem título</title>
<style>
</style>
</head>
<body>
<div style="height:100vh;background-color: tomato;" id="wrap">        
  <h1 class="quote" id="quotee" style="padding-top: 56px">Because too much "light" doesn't <em>illuminate</em> our paths and warm us, it only blinds and burns us.</h1>
</div>
</body>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script>
  var multiplexador = 3;
  initial_div_height = document.getElementById ("wrap").scrollHeight;
  setInterval(function(){ 
    var div = document.getElementById ("wrap");
    var frase = document.getElementById ("quotee");
    var message = "WIDTH div " + div.scrollWidth + "px. "+ frase.scrollWidth+"px. frase \n";
    message += "HEIGHT div " + initial_div_height + "px. "+ frase.scrollHeight+"px. frase \n";           
    if (frase.scrollHeight < initial_div_height - 30){
      multiplexador += 1;
      $("#quotee").css("font-size", multiplexador); 
    }
    console.log(message);          
  }, 10);
</script>
</html>

Solution 18

I did like

let name = "Making statements based on opinion; back them up with references or personal experience."
let originFontSize = 15;
let maxDisplayCharInLine = 50; 
let fontSize = Math.min(originFontSize, originFontSize / (name.length / maxDisplayCharInLine));

Solution 19

I have found a way to prevent the use of loops to shrink the text. It adjusts the font-size by multiplying it for the rate between container's width and content width. So if the container's width is 1/3 of the content, the font-size will be reduced by 1/3 and will container's width. To scale up, I have used a while loop, until content is bigger than container.

function fitText(outputSelector){
    // max font size in pixels
    const maxFontSize = 50;
    // get the DOM output element by its selector
    let outputDiv = document.getElementById(outputSelector);
    // get element's width
    let width = outputDiv.clientWidth;
    // get content's width
    let contentWidth = outputDiv.scrollWidth;
    // get fontSize
    let fontSize = parseInt(window.getComputedStyle(outputDiv, null).getPropertyValue('font-size'),10);
    // if content's width is bigger than elements width - overflow
    if (contentWidth > width){
        fontSize = Math.ceil(fontSize * width/contentWidth,10);
        fontSize =  fontSize > maxFontSize  ? fontSize = maxFontSize  : fontSize - 1;
        outputDiv.style.fontSize = fontSize+'px';   
    }else{
        // content is smaller than width... let's resize in 1 px until it fits 
        while (contentWidth === width && fontSize < maxFontSize){
            fontSize = Math.ceil(fontSize) + 1;
            fontSize = fontSize > maxFontSize  ? fontSize = maxFontSize  : fontSize;
            outputDiv.style.fontSize = fontSize+'px';   
            // update widths
            width = outputDiv.clientWidth;
            contentWidth = outputDiv.scrollWidth;
            if (contentWidth > width){
                outputDiv.style.fontSize = fontSize-1+'px'; 
            }
        }
    }
}

This code is part of a test that I have uploaded to Github https://github.com/ricardobrg/fitText/

Solution 20

I went with geekMonkey solution, but it's too slow. What he does, is he adjusts the font size to maximum (maxFontPixels) and then checks if it fits inside the container. else it reduces the font size by 1px and checks again. Why not simply check the previous container for the height and submit that value? (yes, I know why, but I now made a solution, that only works on the height and also has a min/max option)

Here is a much quicker solution:

var index_letters_resize;
(index_letters_resize = function() {
  $(".textfill").each(function() {
    var
      $this = $(this),
      height = Math.min( Math.max( parseInt( $this.height() ), 40 ), 150 );
    $this.find(".size-adjust").css({
      fontSize: height
    });
  });
}).call();

$(window).on('resize', function() {
  index_letters_resize();
);

and this would be the HTML:

<div class="textfill">
  <span class="size-adjust">adjusted element</span>
  other variable stuff that defines the container size
</div>

Again: this solution ONLY checks for the height of the container. That's why this function does not has to check, if the element fits inside. But I also implemented a min/max value (40min, 150max) so for me this works perfectly fine (and also works on window resize).

Solution 21

Here is another version of this solution:

shrinkTextInElement : function(el, minFontSizePx) {
    if(!minFontSizePx) {
        minFontSizePx = 5;
    }
    while(el.offsetWidth > el.parentNode.offsetWidth || el.offsetHeight > el.parentNode.offsetHeight) {

        var newFontSize = (parseInt(el.style.fontSize, 10) - 3);
        if(newFontSize <= minFontSizePx) {
            break;
        }

        el.style.fontSize = newFontSize + "px";
    }
}