使用JavaScript语句，统计包含“a”或“A”的字符串的个数。第一段代码是正确答案，第二段代码是我写的，看起来和答案一样，但是执行结果只显示数组的第一个字符串，请问这是为什么，检查很久了，，
正确答案：
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8" />
<title>统计包含“a”或“A”的字符串的个数</title>
</head>
<body>
<script type="text/javascript">
var countryList = [
"America",
"Greece",
"Britain",
"Canada",
"China",
"Egypt",
];
var count = 0;
document.write("在以下字符中：<br/>");
for (var i in countryList) {
document.write(countryList[i] + "<br/>");
if (
countryList[i].indexOf("a") != -1 ||
countryList[i].indexOf("A") != -1
)
count++;
}
document.write("共有" + count + "个字符中串包含a或A。");
</script>
</body>
</html>
答案的执行结果如图：
我写的：
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8" />
<title>统计包含“a”或“A”的字符串的个数</title>
</head>
<body>
<script type="text/javascript">
var countryList = [
"abc",
"America",
"Greece",
"Britain",
"Canada",
"China",
"Egypt",
];
var count = 0;
document.write("在以下字符中：<br/>");
for (var i in countryList) {
document.write(countryList[i] + "<br/>");
if (
countryList[i].indexof("a") != -1 ||
countryList[i].indexof("A") != -1
)
count++;
}
document.write("有" + count + "个字符串包含字符a·A " + "<br>");
</script>
</body>
</html>
执行结果：
