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做BS的兄弟都知道js，我們搞Bs就少不了要和js打些交道。不會一定js還真是不行，有些的地方就是離不開js。在form表單中，有時候會要保留小數。精確小數點到多少位。那麼下面的一些方法就可以幫我們做到。</p><p><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><br /><html><br /> <head><br /> <title>floatDecimal.html</title></p><p> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><br /> <meta http-equiv="description" content="this is my page"><br /> <meta http-equiv="content-type" content="text/html; charset=UTF-8"><br /> <script type="text/javascript"><br /> //保留兩位小數<br /> //功能：將浮點數四捨五入，取小數點後2位<br />function toDecimal(x) {<br />var f = parseFloat(x);<br />if (isNaN(f)) {<br />return;<br />}<br />f = Math.round(x*100)/100;<br />return f;<br />}</p><p>//制保留2位小數，如：2，會在2後面補上00.即2.00<br />function toDecimal2(x) {<br />var f = parseFloat(x);<br />if (isNaN(f)) {<br />return false;<br />}<br />var f = Math.round(x*100)/100;<br />var s = f.toString();<br />var rs = s.indexOf('.');<br />if (rs < 0) {<br />rs = s.length;<br />s += '.';<br />}<br />while (s.length <= rs + 2) {<br />s += '0';<br />}<br />return s;<br />}</p><p>function fomatFloat(src,pos){<br /> return Math.round(src*Math.pow(10, pos))/Math.pow(10, pos);<br /> }<br />//四捨五入<br /> alert("保留2位小數：" + toDecimal(3.14159267));<br /> alert("強制保留2位小數：" + toDecimal2(3.14159267));<br /> alert("保留2位小數：" + toDecimal(3.14559267));<br /> alert("強制保留2位小數：" + toDecimal2(3.15159267));<br /> alert("保留2位小數：" + fomatFloat(3.14559267, 2));<br /> alert("保留1位小數：" + fomatFloat(3.15159267, 1));</p><p> //五舍六入<br /> alert("保留2位小數：" + 1000.003.toFixed(2));<br /> alert("保留1位小數：" + 1000.08.toFixed(1));<br /> alert("保留1位小數：" + 1000.04.toFixed(1));<br /> alert("保留1位小數：" + 1000.05.toFixed(1));</p><p> //科學計數<br /> alert(3.1415.toExponential(2));<br /> alert(3.1455.toExponential(2));<br /> alert(3.1445.toExponential(2));<br /> alert(3.1465.toExponential(2));<br /> alert(3.1665.toExponential(1));<br /> //精確到n位，不含n位<br /> alert("精確到小數點第2位" + 3.1415.toPrecision(2));<br /> alert("精確到小數點第3位" + 3.1465.toPrecision(3));<br /> alert("精確到小數點第2位" + 3.1415.toPrecision(2));<br /> alert("精確到小數點第2位" + 3.1455.toPrecision(2));<br /> alert("精確到小數點第5位" + 3.141592679287.toPrecision(5));<br /> </script></p><p> </head></p><p> <body><br /> This is my HTML page. <br><br /> </body><br /></html><br />
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