<script type="text/javascript">

		document.write("请输入要生成随机数的位数：");

			// digit是数字的位数

			function runStr(digit){

				if(digit=="" || isNaN(digit)){

					alert("请输入数字");

				}else{

					var sourceStr="0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G";

					arrStr=sourceStr.split(",");

					var result=""; //定义变量并初始化

					var index=;

					for(i=;i<digit;i++){

						index=parseInt(Math.random()*arrStr.length);

						result+=arrStr[index];

					}

					alert(result);

				}

			}

		</script>

		<form name="form">

			<input type="text" name="digit"/>

			<input type="button" value="生成" onClick="runStr(form.digit.value)">

		</form>