I’ve been wanting to attempt a port of Erik Loyer’s slabtype algorithm for quite some time now and seeing Paravel’s fittext jQuery plugin, in combination with a gloriously hassle-free lunch hour gave me the impetus to attempt it. This is the result – resize the browser viewport to see the effect in action.

So what does the script do again?

Put simply, the script splits headlines into rows before resizing each row to fill the available horizontal space. The ideal number of characters to set on each row is calculated by dividing the available width by the pixel font-size – the script then uses this ideal character count to split the headline into word combinations that are displayed as separate rows of text. Many, many more examples can be viewed further down the page.

Calculated and preset word combinations

While the script does an admirable job at automating the creation of the individual rows, there are certainly situations in which you would choose to control the word combinations used to split the headline.

This can be achieved by presetting the word combinations (using <span class="slabtext"> wrappers) within the markup^[1]. Should the script detect that the headline has been preset, it will not attempt to dynamically create the word combinations and simply fallback to resizing the preset rows to fit the available horizontal space.

Adding the span elements to the page markup in this way gives you absolute control over the word combinations used to split the headline text and also enables the targetting of specific rows within the CSS (in order to tweak the line height, change the font family etc).

Presetting the headline does have its drawbacks though – at smaller sizes and if the rows have wildly varying letter-counts, jagged right edges may be displayed. The script will adjust the word-spacing or letter-spacing in an attempt to rectify over-shoots or under-shoots in line length like this.

The following demo showcases two versions of the same headline, the first has rows (word combinations) dynamically calculated by the script while the second has rows preset within the markup (and therefore only resized-to-fit by the script).

Headers containing links

If the original header contains a link (or should itself have an href set), the generated spans will be wrapped in a link that uses the same href.

Being responsibly responsive

You may wish to remove the slabtext treatment entirely should either the viewport or the header element resize to below a certain, predefined width; for example, if the viewport width drops to below 380 pixels. This can be achievied by using the viewportBreakpoint and headerBreakpoint plugin options, detailed below.

This demo page has set viewportBreakpoint to be 380 pixels. Resizing the browser window to anything below this should remove the slabtext treatment from the headlines altogether.

Behind the scenes

In an attempt to keep the plugin as fast as possible, a very basic font-size calculation is ran whenever the window.resize event fires. Headlines that have been preset only fire steps 1, 2, 6 and, if required, 7 – skipping steps 3 through 5 completely. To save extra cpu cycles, the resize event has been throttled to 300ms.

1. The headlines pixel width is calculated.
2. The headlines pixel font-size is then calculated.
3. The ideal number of “characters per line” is derived by dividing the width (calculated in step 1) by the font-size (calculated in step 2) which itself is multiplied by the font scale ratio (which defaults to 0.78) e.g. for a parent container width of 800 pixels and a font-size of 45 pixels the ideal number of characters per line would be calculated using Math.floor(800 / (45 × 0.78)) = 22.
4. The headline text is then split into words (by splitting on the space character) and these words arranged into combinations containing <= the number of ideal characters per line (calculated in step 3).
5. Each word combination is then wrapped in a <span class="slabtext"> element and the headline markup updated with the new content.
6. Each individual span then has its font-size adjusted by multiplying the current font-size by the ratio difference between the parent containers width (calculated in step 1) and the width of the span.
7. If required, each individual span then has either its letter-spacing (if the line contains only one word) or its word-spacing (if the line contains multiple words) adjusted in an attempt to prod the browser into rectifying over-shoots or under-shoots in line length caused by the previous font-size adjustment.

Plugin options

The following options can currently be passed to the plugin. The first three listed (fontRatio, forceNewCharCount and wrapAmpersand) are only used whenever the plugin has to dynamically create the word combinations i.e. if <span class="slabtext"> elements are not already present within the markup.

fontRatio

A floating point value that is used when calculating the ideal number of “characters per line”. Defaults to 0.78.

forceNewCharCount

A Boolean value that instructs the script to recalculate the ideal number of “characters per line” and reinsert the spans every time the resize event fires (TRUE) or only whenever the parent containers font-size changes (FALSE). Setting this value to FALSE will inevitably save CPU cycles but is only really of use in modern browsers that respond to media queries. Defaults to TRUE.

wrapAmpersand

A Boolean value that instructs the script to wrap ampersands (&) in a <span class="amp"> (TRUE) or not (FALSE). Defaults to TRUE.

maxFontSize

An Integer value that indicates the maximum pixel font-size that the script can set. Defaults to 999.

viewportBreakpoint

An Integer value that indicates the minimum pixel width the viewport may have before the slabtext treatment is removed. There is no default value.

headerBreakpoint

An Integer value that indicates the minimum pixel width the header may have before the slabtext treatment is removed. There is no default value.

noResizeEvent

A Boolean value that instructs the script to ignore the window.resize event (TRUE) or not (FALSE). Useful for those of you using a fixed width layout. Defaults to FALSE.

resizeThrottleTime

An Integer value that indicates the number of milliseconds the window.resize will be throttled to. Defaults to 300.

precision

An Integer value that indicates the decimal precision to use when setting the CSS values line-height, word-spacing and font-size. Defaults to 3.

postTweak

A Boolean value that instructs the script to tweak the line-height or word-spacing after the font-size calculation has been ran (TRUE) or not (FALSE). Defaults to TRUE.

minCharsPerLine

An optional Integer value that indicates the minimum number of characters to set per line. Headlines that have a character count smaller than this value are not given the slabText treatment.

onRender

An optional function that is called every time the script recalculates the headline.

A note on the CSS

The plugin requires the following CSS rules are made available:

.slabtexted .slabtext
    {
    display: -moz-inline-box;
    display: inline-block;
    white-space: nowrap;
    }
.slabtextinactive .slabtext
    {
    display: inline;
    white-space: normal;
    font-size: 1em !important;
    letter-spacing: inherit !important;
    word-spacing: inherit !important;
    *letter-spacing: normal !important;
    *word-spacing: normal !important;
    }
.slabtextdone .slabtext
    {
    display: block;
    }

The span elements added to the headline are given the class slabtext and the document body given the class slabtexted.

Using a double-whammy className inheritance trick like this means that you can safely add the <span class="slabtext"> elements into the markup but they won’t actually get styled until the script gets called and the slabtexted classname added to the body.

The span elements are set as display:inline-block during the font-size calculation. This is to take advantage of the inline-block shrink-wrap effect that enables the script to determine the width of each row.

Unfortunately, one side-effect of using inline-block means that the injected span elements react to surrounding whitespace (which, amongst other things, augments the vertical spacing between rows) – this is remedied by giving the header a classname of slabtextdone whenever the font-size calculation is complete, which sets a display:block style and avoids the whitespace and styling issues associated with inline-block.

Legacy Internet Explorer

Sharp-eyed readers may have noticed that the value of normal is passed to legacy Internet Explorer versions using the star-hack. This is because IE < 8 doesn’t understand the inherit property and so we reset to normal as a failsafe.

Save an HTTP request

The CSS file is miniscule and you may wish to set-up a task runner to concatenate it into your main CSS file during the build process.

Tweaking line-height

Each span element is also given a classname of the form slabtext-linesize-[N] (where N is an Integer value representing the floored result of dividing the character count by ten) and a classname of the form slabtext-linelength-[N] (where N is an Integer value representing the character count). This enables you to target shorter lines that will be rendered at a larger font-size and adjust their line-height accordingly.

Widowed words within headlines

It’s also worth noting that any non-breaking space character used to prevent widowed words within the original, non-adjusted headline will also be included within the adjusted headline.

Buyer beware

Here are a few things to remember when using the plug-in:

1. Headlines with lots of horizontal space to fill are more gracefully displayed across browsers.
2. Headlines with little horizontal space tend to have jagged right edges, especially if the rows have been preset within the markup and each row has a wildly varying letter-count. Firefox appears to be the best at resizing-to-fit the word combinations and some fonts tend to be better than others at being resized-to-fit.
3. The element to be given the slabText treatment has its (inner)HTML replaced entirely (by using the jQuery .html method), which means that all images and links contained within will disappear without a trace.
4. Unlike the original slabtype algorithm, vertical space is not taken into consideration at all.
5. If the header contains multiple links, only the first link located is taken into account.
6. Internet Explorer 6, due to its non-support of inline-block, cannot scale down the text when the browser viewport is reduced in width. This will not be an issue if you serve a fixed width design to IE6 and fluid width design to other, more capable browsers.
7. Internet Explorer < 8 does not support the CSS value of inherit which means that the letter-spacing and word-spacing have to get reset to zero whenever the slabText treatment is removed by the script.
8. Always call the script after all fontface fonts have downloaded. I’ve used the google fontloader fontactive() and fontinactive() callbacks to launch the slabText treatment in the demo.

Credit where credit’s due

Based on the nice, shiny fittext jQuery plugin by Paravel & the wonderful slabtype algorithm by Erik Loyer. Zach Leatherman has also written a jQuery plugin named BigText with similar but not exact functionality which is well worth a visit.

Grab the code

The code can be downloaded from github. Both minified and unminified versions are included within the bundle. The minified version currently clocks-in at 3k – this drops to around 2k when gzipped.

A few more examples

As way of example, here’s a random assortment of book titles (Note: I’ve left widowed words in all of them).