You realize how funny the technology world is when you come upon a technology from 2005 and are immediately distrusting and suspicious that it has already been replaced with something new. “Two years ago!? How antiquated! I’m sure by now we’ve tackled the problem with an extra embedded API added on for ordering triple half-calf mocha skim ole 2% orange juice lattes wearing a bathing suit! … from Emacs!”

You understand my suspicions, I’m sure.

So I begin with my distrust, but ultimately feel compelled to express my excitement about the ability to abuse the the E4X extension of JavaScript to handle multi-line strings. For those who don’t know (I sure didn’t), E4X stands for ECMAScript for XML (E4X) and was introduced in 2004 and subsequently updated in 2005. It appears that Mozilla-based browsers support it, but I’m not so sure about IE (grumble).

The gist is this: JavaScript doesn’t support multi-line strings, which is a bummer. Ruby has it. So does Python. Even C# does, with the @” quote. You’d think peer pressure alone would have forced JavaScript to adopt it, not to mention the common need to assemble long chunks of HTML from within JavaScript, but it still ain’t so. E4X provides a sneaky way to accomplish it, however, by embedding the string within HTML tags. E4X is essentially a way to use DOM fragments as native JavaScript objects, so you can have a variable defined like this:

    var address = "" + (<r><![CDATA[
    127 Prime Ln.
    55005
    ]]></r>);

The developer gets all sorts of nifty ways to interact with this data, but the toString function is the sneak-route for abuse. Let’s say we want to construct a multi-line string for some poetry:

    var htmlFragment = "" + (<r><![CDATA[
    l(a
    
    le
    af
    fa
    
    ll
    
    s)
    one
    l
    
    iness
    
    - e.e. cummings
    ;
    ]]></r>);

Or perhaps we want to construct a fragment of HTML from with JavaScript but don’t want to use a builder:

    var htmlFragment = "" + (<r><![CDATA[
    <div id="somethingorother">
      <ol>
        <li>Item 1</li>
        <li>Item 2</li>
      </ol>
    </div>
    ]]></r>);

Why in the world would you put your HTML inside a CDATA block, you say? For a top secret project, I tell you! The variable htmlFragment now contains this multiline string, since the the “”+ at the beginning caused the subsequent E4X DOM fragment to be cast as a string for concatenation. Test it out for yourself by setting the innerHTML of your page body to the variable above.

    $('the_body').innerHTML = htmlFragment;

Pretty clever…