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<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<META NAME="Generator" CONTENT="EditPlus">
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<script type="text/javascript">
testVar1();
testVar();
alert(test);//輸出Hello!
alert(test1);//輸出時報錯,test1未被定義
function testVar1()
{
var test1="Hello1!";
}
function testVar()
{
test="Hello!";
}
</Script>
</BODY>
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通過執行個體程式分析javaScript function內的變數問題,不用var申明與用var申明的區別。
結論：
1、在javaScript function內不用var申明的變數等同全域變數,即在javaScript function外可見,但使用該變數之前要先調用對應的javaScript function.
2、在javaScript function內使用var申明的變數等同局部變數,其可見度只在對應的javaScript function內部.
3、建議在使用之前顯示定義變數,這樣程式可讀性和維護效能才比較好.盡量不用使用第一條裡面的方法.
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