JavaScript隨機數產生方法

實現隨機數是各種程式設計語言都很常見的一個編程任務，下面介紹一下在JavaScript如何?隨機數。第一中方法通過重寫Math.random方法實現，第二種方法改自一個C實現，都可以實現編程目的。

直接上代碼：

    <script language="javascript">    var native_random = Math.random;Math.random = function(min, max, exact) {if (arguments.length === 0) {return native_random();} else if (arguments.length === 1) {max = min;min = 0;}var range = min + (native_random()*(max - min));return exact === void(0) ? Math.round(range) : range.toFixed(exact);};document.write(Math.random());document.write('<br />');document.write(Math.random(10));document.write('<br />');document.write(Math.random(3,10));document.write('<br />');document.write(Math.random(2,10,4));</script>

程式運行結果如下：

0.2989420900121331792.2469

如何不使用Math.random實現隨機數呢？下面的函數改自一個C實現：

var random = (function(){var high = 1, low = 1 ^ 0x49616E42;var shuffle = function(seed){high = seed;low = seed ^ 0x49616E42;}return function(){    var a = new Date()-0     shuffle(a);    high = (high << 16) + (high >> 16);    high += low;   low += high;     return high; }})(); p(random());

<script type="text/javascript">var random = (function(){var high = 1, low = 1 ^ 0x49616E42;var shuffle = function(seed){high = seed;low = seed ^ 0x49616E42;}return function(){ var a = new Date()-0 shuffle(a); high = (high << 16) + (high >> 16); high += low; low += high; return high; }})(); alert( random() );</script>