understanding function inside function .

hey guys have a look at the below function , very simple and straightforward :

[CODE]function countdown (sec, onTick) {
onTick(sec);
if (sec) setTimeout(function () {
countdown(–sec, onTick);
}, 1000);
}

onload = function () {
countdown(5, function (sec) {
console.log(sec ? sec + ‘ ‘ : ‘BOOM!’);
});
};

onload();[/CODE]

what is the js terminology for “countdown” inside the onload function ?

Thank you.

Gautam.

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