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JavaScript? ?? ?? ??

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toFixed()

  • ??: ? ?? ??? ?? ???? ????? ???? ???? ??????.

  • ??: numObj.toFixed(n)

  • ????: n? ??? ??? ?? ??????.

  • ?:

var a = 123.9878;

a = a.toFixed(2); // a = "123.99"

<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script>
            var x=134.456756;
            document.write(x.toFixed(3));
        </script>
    </head>
    <body>
    </body>
</html>

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<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>php.cn</title>
        <script>
            //求圓的面積
            function getArea(r){
                var s=Math.PI*r*r;
                s=s.toFixed(4);
                document.write("半徑為:"+r+"的圓，面積為:"+s+"<br/>");
            }
            getArea(2);
            getArea(4);
            getArea(5);
        </script>
    </head>
    <body>
    </body>
</html>


???? ??
||
<!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>php.cn</title> <script> var x=134.456756; document.write(x.toFixed(3)); </script> </head> <body> </body> </html>