在某两个数范围内的随机数公式：Math.random() * (end - 1) + start

indexOf判断是否有重复 

<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script>
		
			
			const _getUniqueNums = (start, end, n) => {
				// 补全代码
				let arr = []
				
				for (var i = 0; i < n; i++) {
					let ran = Math.floor(Math.random() * (end - 1) + start)
					if(arr.indexOf(ran) == -1){
						arr.push(ran)
					}
					
				}
				
			}
			
		</script>
	</body>
</html>