SOURCE

function isFirstLoad () {
	var _list = [];
	return function (id) {
		if (_list.indexOf(id) >=0) {
			return false
		}else {
			_list.push(id);
			return true
		}
	}
}
var load = isFirstLoad();
console.log(load(10))
console.log(load(10))
console.log(load(20))