js 四舍五入保留一位小数怎么写

在JavaScript中，可以使用Math.round()方法来实现四舍五入保留一位小数。下面是一个示例代码：

var num = 1.2345;
var roundedNum = Math.round(num * 10) / 10;
console.log(roundedNum); // 输出 1.2

在这个例子中，我们将要保留一位小数的数字乘以10，然后使用Math.round()方法对结果进行四舍五入，再除以10，得到保留一位小数的结果。
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