生成随机数

    
<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>