sample: random increment variable
by sii_side
HTML
<button>0</button>
JavaScript
var cnt = 0;
$("button").on("click", function() {
var tmp = cnt;
var rnd = Math.random();
if(rnd < 0.5) {
cnt++;
}
if(cnt === tmp) {
window.alert("not increment");
} else {
$(this).text(cnt);
}
});