js实现输入几位就几位的随机验证码

下面这个是我输入3混合型字符 并且10位的随机数

 

 下面是js代码

这是一种比较原始的方法 简单易懂

	<script type="text/javascript">
function numder(aaa = "numder", s = 4) {
					var a = ["q", 'w', 'e', 'r', 't', 'y',
						'u', 'i', 'o', 'p', 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'z', 'x', 'c', 'v', 'b', 'n', 'm'
					]
					var b = ['1', '2', '3', '4', '5', '6', '7', '8', '9', '0']
					var c =["q", 'w', 'e', 'r', 't', 'y',
						'u', 'i', 'o', 'p', 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'z', 'x', 'c', 'v', 'b', 'n', 'm',
					'1', '2', '3', '4', '5', '6', '7', '8', '9', '0']
					var qq = "";
					if (aaa == "1") {
						for (var i = 0; i < s; i++) {
							var index = Math.random() * b.length;
							index = Math.floor(index);
							var rgb_r = Math.random() * 255
							var rgb_g = Math.random() * 255
							var rgb_b = Math.random() * 255
							qq += "<b style='color:rgb(" + rgb_r + "," + rgb_g + "," + rgb_b + ")'>" + b[index] + "</b>";
						}
						return qq;
					}else if(aaa=="2"){
						for (var i = 0; i < s; i++) {
							var index = Math.floor(Math.random() * a.length);
							var rgb_r = Math.random() * 255
							var rgb_g = Math.random() * 255
							var rgb_b = Math.random() * 255
							qq += "<b style='color:rgb(" + rgb_r + "," + rgb_g + "," + rgb_b + ")'>" + a[index] + "</b>";
						}
						return qq;
					}else if(aaa=="3")
					for (var i = 0; i < s; i++) {
						var index = Math.floor(Math.random() * c.length);
						var rgb_r = Math.random() * 255
						var rgb_g = Math.random() * 255
						var rgb_b = Math.random() * 255
						qq += "<b style='color:rgb(" + rgb_r + "," + rgb_g + "," + rgb_b + ")'>" + c[index] + "</b>";
					}
					return qq;
				}
				var a=prompt("请输入：1数字型,  2字符型,  3混合型")
				var b =parseFloat(prompt("请输入验证码长度")) 
				document.write(numder(a,b));
	</script>