大写的尴尬席梦瑶:js初学者问个基本的看不懂

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aString = "0123456789";
var aChunk = aString.substring(4, 7); // 将 aChunk 设为 "456"。
var aNotherChunk = aString.substring(7, 4); // 将 aNotherChunk 设为 "456"。
// 使用上面生成数组的示例:
firstLetter = theMonths[5].substring(0,1); // 将变量 firstLetter 设为“J”。

j 是怎么实现设

搜索了一下,原来是个教程,看一下教程,对数组的赋值~

<script language="javascript">
var theMonths = new Array("Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec");
function test()
{
var theMonths = new Array("Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec");
alert(theMonths[5])
}
function test1()
{
firstLetter = theMonths[5].substring(0,1);
alert(firstLetter)
}
</script>
<input type="button" name="a" onclick="test()" value="theMonths[5]">
<input type="button" name="a" onclick="test1()" value="theMonths[5].substring(0,1)">

<HTML>
<BODY>
<SCRIPT LANGUAGE="JavaScript">
var theMonths = new Array(6);
var firstLetter;
theMonths[5] = 'Jun';
firstLetter = theMonths[5].substring(0,1);
alert(firstLetter);
</script>
</BODY>
</HTML>

substring 是取字符串中的部分字符的函数。
theMonths 是数组。theMonths[5]是数组中第6个元素。