JavaScript 条件分支语句if...else

本文主要是介绍JavaScript 条件分支语句if...else，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

if 语句

只有当指定条件为 true 时，该语句才会执行代码

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body><script>var sum = 300var youhuisum if(sum>200){youhuisum = sum - 10}console.log(sum,youhuisum)</script>
</body>
</html>

if else语句

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body><script>var sum = 150var youhuisum if(sum>200){youhuisum = sum - 10}else{youhuisum = sum}console.log(sum,youhuisum)</script>
</body>
</html>

if...else if...else if语句

后面可以无限跟else if

总金额sum是100.

如果总金额大于200，youhuisum就减10元，否则就继续判断总金额是否大于100，如果sum大于100，youhuisum就减20元以此类推

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body><script>var sum = 20var youhuisum if(sum>200){youhuisum = sum - 10}else if(sum>100){youhuisum = sum - 20}else if(sum>50){youhuisum = sum - 30}else{youhuisum = sum}console.log(sum,youhuisum)</script>
</body>
</html>