筆試題 做用域

變量提高 做用域

外部引用的函數做用域在外面。。。沒法訪問內部函數，能夠經過參數添加 如（2）


var number =3;
function getNumber() {
	return number;
}

var getNumber2 = (function(){
	number =4;
	var number;
	number = number*2;
	return getNumber;

})()
alert(getNumber2());
alert(getNumber())

(2)
var number =3;
function getNumber(nuber) {
	return number;
}

var getNumber2 = (function(){
	number =4;
	var number;
	number = number*2;
	return getNumber（number）;

})()
alert(getNumber2());
alert(getNumber())

　　

var number =3;
function getNumber() {
	return number;
}

var getNumber2 = (function(){
	number =4;
	var number;
	number = number*2;
	return getNumber;
	function getNumber(){
		return number;
	}
})()
alert(getNumber2());
alert(getNumber)


變量提高，覆蓋