while loop in JavaScript
while loop: As long as the condition is true, the loop body code will be executed repeatedly
while (conditional judgment)
{
If the condition is true, the loop body code will be executed
}
While loop structure description:
Before the loop starts, it must Initialize the variable (declare the variable and give the variable an initial value).
If the condition of while is true, the code ({ }) in the loop body will be executed repeatedly. If the condition is false, exit the loop.
In the loop body, there must be a "variable update" statement. In other words: the values of the variables in the two loops cannot be the same. If they are the same, it will cause an "infinite loop".
Let’s learn through examples:
Output all numbers between 1-10
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>php.cn</title>
<script>
var i = 1;
while(i<=10){
document.write(i);
i++ //变量更新，是为了避免出现“死循环”
}
</script>
</head>
<body>
</body>
</html>Loop statement There must be three elements, one of which is indispensable:
Variable initialization
Conditional judgment
Variable update
Output all odd numbers between 1-100
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>php.cn</title>
<script>
//变量初始化
var i = 1;
//条件判断
while(i<=100){
//如果是奇数，则输出
if(!(i%2==0)){
document.write(i+" ");
}
//变量更新
i++;
}
</script>
</head>
<body>
</body>
</html>
