<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<title></title>
</head>
<body>
<script>
var str ="Rome was not built in a day"; //字符串
arr =str.replace(/\s/g); //去掉所有的空格
var sum =0; //定义一个总和
for(var i of str)
{
sum++;
} //利用for循环统计字符串的字符个数
document.write(sum); //输出字符串中字符的个数
</script>
</body>