標籤：val tns function head core back 表達 for blank
在一些進階語言如C#中，switch分支的值只能是常量，而js中可以是變數或運算式：
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <title>Document</title> <script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js"></script> <script type="text/javascript"> $(function(){ $(‘#btnScore‘).bind(‘click‘,function(){ var score = $(‘#txtScore‘).val(); var reg = /^[0-9]+.?[0-9]*$/ if (!reg.test(score)) { alert(‘請輸入合法的數字！‘); return false; } calcScore(score); }) }); function calcScore(score){ switch(true){ //不能寫switch(score)，因為運算式值為bool類型 case score > 90 && score <= 100: alert(‘優‘); break; case score > 80 && score <= 90: alert(‘良‘); break; case score > 59 && score <= 80: alert(‘及格‘); break; case score > -1 && score <= 59: alert(‘不及格‘); break; default: alert(‘輸入分值範圍錯誤！‘); break; } } </script></head><body> <label for=‘txtScore‘>分值：</label><input id=‘txtScore‘ type=‘text‘> <input id=‘btnScore‘ type=‘button‘ value=‘評分‘ /></body></html>
運行效果
js中switch/case分支的值可以是變數或運算式
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