Javascript is by it's nature asynchronous, which makes returning data from an AJAX call complicated. Modern Javascript uses the concept of a "promise" to allow you to run code after an asynchronous call competes. This is similar to using a callback function, but it reads cleaner. JQuery implements this type of call with the then() function. A simple example is as follows:

function getData() {
    return $.ajax({
        url: '/api/data'
    });
}

// Usage
getData().then(function(data) {
    console.log(data);
});

I needed a modern way to copy a string to the clipboard in JavaScript. Claude.ai helped me come up with this:

// With async/await
async function copyToClipboard(text) {
    try {
        await navigator.clipboard.writeText(text);
        console.log('Copied to clipboard');
    } catch (err) {
        console.error('Failed to copy: ', err);
    }
}

Then you simply call it with a string

copyToClipboard("Hello world");

I need a Unixtime in Javascript. This is the simplest way I came up with to get that value:

var unixtime = parseInt(new Date().getTime() / 1000);

Update: Newer versions of Javascript (and browsers) now offer Date.now() which returns milliseconds since the epoch with less typing required.

var unixtime = parseInt(Date.now / 1000);

I always end up trying to figure out what a unixtime is in human readable format, or vice versa. I ended up borrowing and updating a tool from captain.at, striping out all the ads and other junk and cleaning it up so it's XHTML compliant. Check out my new and improved javascript unixtime converter.

There is going to be a leap second today at 1230768000 (2008 December 31, 23h 59m 60s). I updated my Javascript Unixtime converter to include options for UTC time. Happy Leap Seconds!

Just a note of how to get Unixtime in Javascipt.

var date_obj    = new Date;
var unixtime_ms = date_obj.getTime();
var unixtime    = parseInt(unixtime_ms / 1000);

Also a Javascript Unixtime conversion utility.

I am late to the game learning about the Mustache templating language. It is very mature, and has support for all of the languages I care about: Perl, PHP, and Javascript. I am mainly focused on using it in Javascript as it is a great way to format raw data you get via JSON into something more human consumable like HTML.

It's incredibly easy to implement and get started with. A single include loads the entire zero-dependency library. As of v4.2.0 the library is tiny, clocking in at only 25k. Once loaded Mustache.render(template_str, data_obj) gets you a formatted string. A big selling point is the ease of installation and use. You can be up and running with Mustache.js in less than 5 minutes.

<script src="/js/mustache.min.js"></script>

var data = { name: "Jason", animal: "Kitten" };
var str  = Mustache.render("<p>Hello {{name}}, I hear you like {{animal}}s</p>", data);

I liked it so much I wrote up a Mustache sandbox to allow me to play around with the templating system live. The template syntax is a little archaic, but it is workable.

Note: They even have Arduino support, which I need to test.