javascript自动生成包含数字与字符的随机字符串

本文实例讲述了javascript自动生成包含数字与字符的随机字符串的方法。分享给大家供大家参考。具体如下：

这里主要用到Math.random() 和 Math.floor() 两个函数

Math.random()   -- 返回0和1之间的伪随机数 可能为0，但总是小于1，[0,1)

Math.floor()    -- 向下取整，舍掉小数字后的值

实现随机多位数的方法：

/**
*
*    随机生成数字
*
*@param num 生成数字位数
*/ 
function randomNumber(num){ 
        return ''+Math.floor(Math.random() * num) ; 
}

javascript 随机生成字符

以下实例为随机 A-Z / a-z区间 中随机出现的字符

/**
 *
 *    随机生成
 *
 *@param data json数据 例：{"start":0,"end":2,"number":5,"upper":true} 
 *@param start  开始下标
 *@param end    结束下标
 *@param number 生成位数
 *@param upper  是否大写 默认为小写
 */ 
function randomLetter(data){ 
    var letterData = ""; 
    var lowercase = new Array("a","b","c","d","e","f","g","h","i","g","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"); 
 
    var uppercase = new Array("A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"); 
    var start = data.start; 
    var end = data.end; 
    var number = data.number; 
    var upper = data.upper; 
 
    var length = end - start; 
    for(var i= 0;i < number; i++){ 
        var index = Math.floor(Math.random() * length) + start; 
        var letter = ""; 
        if(upper){ 
            letter = uppercase[index]; 
        }else{ 
            letter = lowercase[index]; 
        } 
        letterData += letter; 
    } 
    return letterData;  
}

引用：

alert(new Date().Format("yyyy-MM-dd hh:mm:ss"));

希望本文所述对大家的javascript程序设计有所帮助。