console
function writeDocument(variable) {
document.write(variable + "<br/>");
}
//1.如果有一个字符串"Rome was not built in a day"
//请用程序统计该字符串中字符的个数
//不允许使用字符串对象的length属性。
writeDocument("-------------------1.Rome was not built in a day-------------------");
var sentence="Rome was not built in a day";
var total=0;
for (var i of sentence){
total++;
}
document.write("Rome was not built in a day一共有"+total+"个字符串"+ '<br/>');
writeDocument("--------------------------------------------------------------------------");
//2.给大家一个任意的字符串
//如何实现把字符串中的字符顺序颠倒
//如给你"abcde"，你要得到"edcba"。
writeDocument("-------------------------2.给abcde，得到edcba-------------------------");
function Contrary(letters){
var a=[];
for(var i=letters.length-1;i>=0;i--){
//用push()在数组结尾添加新元素，并且得到一个新的数组
a.push(letters[i]);
}
//用join()将数组中的所有元素连接成一个字符串
return a.join("");
}
document.write(Contrary("abcde")+'<br/>');
writeDocument("--------------------------------------------------------------------------");
//3.利用3种循环来计算1+2+3+…+100的值。
writeDocument("-----------------------3.计算1+2+3+…+100的值-----------------------");
//1)while循环
writeDocument("1)while循环");
var num1=0;
var i=0;
while(i<100){
i++;
num1+=i;
}
document.write("1+2+3+…+100="+num1+'<br/>');
writeDocument("--------------------------------------------------------------------------");
//2)do while
writeDocument("2)do while循环");
var num2=0;
var i=0;
do{
i++;
num2+=i;
}while(i<100);
document.write("1+2+3+…+100="+num2+'<br/>');
writeDocument("--------------------------------------------------------------------------");
//3)for循环
writeDocument("3)for循环");
var num3=0;
for(i=1;i<=100;i++){
num3+=i;
}
document.write("1+2+3+…+100="+num3+'<br/>');
writeDocument("--------------------------------------------------------------------------");
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<script>
</script>
</head>
<body>
</body>
</html>