Bookmarklets are the handiest little things. In case you don't know (which I'm sure you do), they're small chunks of JS that you store in your browser's Bookmarks or Favourites section which you can launch while looking at any web page. I write bookmarklets for all kinds of different tasks – navigating quickly around the build monitor at work, filling in tricky forms that my browser autocomplete doesn't handle, etc.

Here are a few of bookmarklets I find extremely useful for web development. To add them to your browser, simply drag the link on the title into your bookmark bar, hold shift down and drag or right-click and 'Add to Favourites', depending on what browser you're in.

Add JS to the page by URL

This will allow you to add any script you like to the current page. This can be particularly useful if you want to add a certain library or plugin to a page to investigate it further.

javascript:(function(){document.body.appendChild(document.createElement('script')).src=prompt('Script to add');})();

Add the latest CDN jQuery to the page

A variation on the above bookmarklet, this simply adds the latest version of jQuery. If you want to be able to play with a page and are familiar with jQuery, this will ensure that it is loaded and attached.

javascript:(function(){document.body.appendChild(document.createElement('script')).src='http://code.jquery.com/jquery-latest.min.js'})();

Add CSS to the page by URL

Add any stylesheet to the current page with a particular URL. This is handy if you want to demo variations to clients, I find. particularly if you predefine the CSS URL.

javascript:(function(d){if(d.createStyleSheet)%20{d.createStyleSheet(%20u%20);}%20else%20{var%20css=d.createElement(%27style%27),u=prompt(%27CSS%20to%20add%27);css.setAttribute(%22type%22,%22text/css%22);css.appendChild(document.createTextNode(%22@import%20url(%22+u+%22)%22));d.getElementsByTagName(%22head%22)[0].appendChild(css);}}(document))

Submit this page to the webdev subreddit

This isn't so much a web dev helper, more a general helper. I use this (or a variation thereof) to submit posts to specific reddits with fields prefilled. This bookmarklet defaults to the webdev subreddit.

javascript:window.location=%22http://www.reddit.com/r/webdev/submit?url=%22+encodeURIComponent(window.location)+'&title='+encodeURIComponent(document.title);void(0);

Add a CSS rule to the page

I can't remember whether I wrote this one or if I found it somewhere. The 'x<style>' is something from the middle of jQuery, though. Anyhow.

This allows you to add a style block directly into the page. This is useful for small CSS injections where the browser's web inspector is unavailable or incapable. Even though it's a single prompt that pops up, there's no reason why you can't past an entire stylesheet in there. I sometimes find myself doing that when I'm previewing designs on a production server.

javascript:(function(){var div = document.createElement('div'); div.innerHTML ='x<style>' +prompt('Style to add')+ '</style>';document.body.appendChild(div.lastChild);})();

While putting together last week's promo video for Museum140 (a vote'd be awsm, btw), I knocked up a few tools to make my life easier. As I always say, if you find something you like, make a plugin for it. Seriously, I always say that. That might even be how I proposed to my wife, I'll have to check.

Anyway.

Play

This is a simple timing helper. It just provides a little array you can push slide durations into and at the end, you call 'play'. I can't see many uses for this other than in creating videos.

ImpressJS.play(3000);  //Set the first slide duration for 3 seconds
ImpressJS.play(1000);  //Set the second slide duration for 1 second
ImpressJS.play(); //Play from the start

Edit

This is much more useful.

If this script is included in the page (after the impress.js script), you can drag your slides around, rotate and scale them into exactly the position you want. Once you're happy, you can get the current HTML output onto the console for pasting back into your original slideshow file. I could have snuck in a drag-n-drop file handler but that would make it Chrome only.

Disclaimer

These tools rely on ImpressJS having a public API which it currently doesn't have. It's obviously high on the author's priority list (given the amount of discussion it's raised) but, as too many pull requests spoil the broth, I've made a little fork of my own, added the public functions the tools require and I'll update them once the main repository's settled down a bit.

Download

These are available in the tools folder of this fork of impress.js. Each one contains an example. Hopefully, these will be updated to use the public API as soon as it's available.

Here's a useful little code snippet if you're building a web application. It's a simple way of making the boundary between web-browser and platform a bit smaller. It allows you to create a file (text, html, whatever) in in your page which the user can drag onto their desktop (if their browser supports the dragstart event and dataTransfer methods).

document.getElementById('downloadElement').addEventListener("dragstart", function (e) {
  e.dataTransfer.setData("DownloadURL", "text/html:filename.html:data:image/png;base64," + btoa(fileContent));
});

A description of the code:

• attach an event listener to the draggable element you specify (downloadElement)
• when you start to drag it (dragstart),
• it creates a dataTransfer object (with the type DownloadURL)
• and sets the content of that to be whatever you pass it (fileContent)
• It uses btoa() to encode the string data as a base64-encoded string.
• When you combine this with the MIME-type (text/html),
• you can create a file with the specified name (filename.html) when the user releases the drag in their local file system.
• The fake MIME-type (image/png) is there as part of the object data to convince the browser this is a binary file (which it is, even though it's not an image).

Credit goes to Paul Kinlan for using this in Appmator which is where I first saw this done this way. He actually uses it alongside some extremely clever JS zip-file creation stuff, too, it's definitely worth digging through the source there.

You can find out more about the drag events on the MDN.