用JS編寫計算器

Javascript相當只簡潔方便，頗有MATLAB之風

這是曾經web課上的作業，用js寫個簡單的計算器

這里關鍵是定義計算器的函數，首先看js定義函數的語法：

[javascript]?view plaincopy

function?func1(…){…};??

var?func2=function(…){…};??

var?func3=function?func4(…){…};??

var?func5=new?Function();??

Js中每個變量包括函數都需要作為一個對象來運營維護。

直接貼上計算器的代碼：

[javascript]?view plaincopy

<script?language="javascript"?>??

??

??

//計算中要用到的變量??

var?formulaToShow="";??//要顯示的計算式??

var??formulaToCalcu="";//要計算的計算式??

var?result="?";??//計算結果??

var?saved="0";???//存儲的數??

??

??

//生成計算式的函數??

function?TypeFormula(com)??

{??

??//如果是已經求過值，則清屏并重新開始計算??

??if((result!="?"||result=="0")?&&?com!="save"){??

????formulaToShow="";??

????result="?";??

??}??

????

??//得到按鈕信息??

??switch(com)??

??{??

????case?"clear"://清空??

???????formulaToShow="";??

???????result="?";??

???????break;??

?????case?"back"://退格（這個寫的有些冗余）??

???????{var?f=formulaToShow;??

???????if(f.substring(f.length-5,f.length)=="asin("||f.substring(f.length-5,f.length)=="acos("||f.substring(f.length-5,f.length)=="atan("||f.substring(f.length-5,f.length)=="sqrt(")??

?????????formulaToShow=formulaToShow.substring(0,formulaToShow.length-5);??

???????else?if(f.substring(f.length-4,f.length)=="sin("||f.substring(f.length-4,f.length)=="cos("||f.substring(f.length-4,f.length)=="tan("||f.substring(f.length-4,f.length)=="exp(")??

?????????formulaToShow=formulaToShow.substring(0,formulaToShow.length-4);??

???????else?if(f.substring(f.length-3,f.length)=="ln(")??

?????????formulaToShow=formulaToShow.substring(0,formulaToShow.length-3);??

???????else???

?????????formulaToShow=formulaToShow.substring(0,formulaToShow.length-1);??

???????}??

???????break;???????

???????

?????case?"sign":??

???????{if?(formulaToShow=="")formulaToShow="-";??

???????else?if(formulaToShow[0]=="-")formulaToShow=formulaToShow.substring(1,formulaToShow.length);??

???????else?formulaToShow="-"+formulaToShow;}??

???????break;??

???????case?"save":??

?????????saved=formulaToShow;??

??????break;??

??????case?"getsave":??

?????????formulaToShow=formulaToShow+saved;??

??????break;??

??????case?"result"://計算結果??

???????{if(formulaToShow=="")?result="?";??

???????else?{??

?????????formulaToCalcu=formulaToShow.toString();??

?????????formulaToCalcu=formulaToCalcu.replace(/sin/g,?"Math.sin");??

?????????formulaToCalcu=formulaToCalcu.replace(/cos/g,?"Math.cos");??

?????????formulaToCalcu=formulaToCalcu.replace(/tan/g,?"Math.tan");??

?????????formulaToCalcu=formulaToCalcu.replace(/asin/g,?"Math.asin");??

?????????formulaToCalcu=formulaToCalcu.replace(/aMath.sin/g,?"Math.asin");??

?????????formulaToCalcu=formulaToCalcu.replace(/acos/g,?"Math.acos");??

?????????formulaToCalcu=formulaToCalcu.replace(/aMath.cos/g,?"Math.acos");??

?????????formulaToCalcu=formulaToCalcu.replace(/atan/g,?"Math.atan");??

?????????formulaToCalcu=formulaToCalcu.replace(/aMath.tan/g,?"Math.atan");??

?????????formulaToCalcu=formulaToCalcu.replace(/exp/g,?"Math.exp");??

?????????formulaToCalcu=formulaToCalcu.replace(/ln/g,?"Math.log");??

?????????formulaToCalcu=formulaToCalcu.replace(/sqrt/g,?"Math.sqrt");??

??

???????try?{result=eval(formulaToCalcu);}??

???????catch?(exception)?{??

?????????????????window.alert(exception);?}??

?????????}??

???????}??

???????break;??

???????default:??

???????formulaToShow+=com;???

???????break;??

??}??

??

???txtShow.innerHTML=formulaToShow+"<br/>"+result+"<br/>";????

}??

??

</script>??

我們可以使用很多內置的函數，如sin() ?cos()等

下面是計算器截圖：

轉載請注明出處：http://blog.csdn.net/xiaowei_cqu/article/details/7081348

源碼下載：http://download.csdn.net/detail/xiaowei_cqu/3935914

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