Long Press in JavaScript?

There is no 'jQuery' magic, just JavaScript timers.

var pressTimer;

$("a").mouseup(function(){
  clearTimeout(pressTimer);
  // Clear timeout
  return false;
}).mousedown(function(){
  // Set timeout
  pressTimer = window.setTimeout(function() { ... Your Code ...},1000);
  return false; 
});

You can use taphold event of jQuery mobile API.

jQuery("a").on("taphold", function( event ) { ... } )

Based on Maycow Moura's answer, I wrote this. It also ensures that the user didn't do a right click, which would trigger a long press and works on mobile devices. DEMO

var node = document.getElementsByTagName("p")[0];
var longpress = false;
var presstimer = null;
var longtarget = null;

var cancel = function(e) {
    if (presstimer !== null) {
        clearTimeout(presstimer);
        presstimer = null;
    }

    this.classList.remove("longpress");
};

var click = function(e) {
    if (presstimer !== null) {
        clearTimeout(presstimer);
        presstimer = null;
    }

    this.classList.remove("longpress");

    if (longpress) {
        return false;
    }

    alert("press");
};

var start = function(e) {
    console.log(e);

    if (e.type === "click" && e.button !== 0) {
        return;
    }

    longpress = false;

    this.classList.add("longpress");

    if (presstimer === null) {
        presstimer = setTimeout(function() {
            alert("long click");
            longpress = true;
        }, 1000);
    }

    return false;
};

node.addEventListener("mousedown", start);
node.addEventListener("touchstart", start);
node.addEventListener("click", click);
node.addEventListener("mouseout", cancel);
node.addEventListener("touchend", cancel);
node.addEventListener("touchleave", cancel);
node.addEventListener("touchcancel", cancel);

You should also include some indicator using CSS animations:

p {
    background: red;
    padding: 100px;
}

.longpress {
    -webkit-animation: 1s longpress;
            animation: 1s longpress;
}

@-webkit-keyframes longpress {
    0%, 20% { background: red; }
    100% { background: yellow; }
}

@keyframes longpress {
    0%, 20% { background: red; }
    100% { background: yellow; }
}