標籤：style class blog code java http
<!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml"><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title></title> <script type="text/javascript"> //1.js 頂級範圍 是window var num = 1; alert(window.num); //2 方法範圍 function test() { number2 = 2;//方法內部聲明局部變數的時候，需要加var 否則就是全域變數 var num3 = 3;//局部變數在方法外部無法訪問 //3 沒有塊級範圍 for (var i = 0; i < 10; i++) { var num4 = 4; } alert(num4); //因為沒有塊級範圍，所以此處的變數num4就是方法的一個局部變數 } test(); alert(window.number2); </script></head><body></body></html>
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