javascript 四舍五入到最接近的 0.5 位小数
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Round number to nearest .5 decimal
提问by iamwhitebox
I'm looking for an output of
我正在寻找输出
4.658227848101266 = 4.5
4.658227848101266 = 4.5
4.052117263843648 = 4.0
4.052117263843648 = 4.0
the closest I've gotten is
我得到的最接近的是
rating = (Math.round(rating * 4) / 4).toFixed(1)
but with this the number 4.658227848101266 = 4.8???
但是有了这个数字 4.658227848101266 = 4.8？？？
回答by Dave
(Math.round(rating * 2) / 2).toFixed(1)
回答by Ignacio A. Rivas
It's rather simple, you should multiply that number by 2, then round it and then divide it by 2:
这很简单，您应该将该数字乘以 2，然后将其四舍五入，然后再除以 2：
var roundHalf = function(n) {
return (Math.round(n*2)/2).toFixed(1);
};
回答by cardern
This works for me! (Using the closest possible format to yours)
这对我有用！（使用最接近您的格式）
rating = (Math.round(rating * 2) / 2).toFixed(1)
回答by mr haven
So this answer helped me. Here is a little bit o magic added to it to handle rounding to .5 or integer. Notice that the *2 and /2 is switched to /.5 and *.5 compared to every other answer.
所以这个答案对我有帮助。这里添加了一点点魔法来处理四舍五入到 0.5 或整数。请注意，与其他所有答案相比，*2 和 /2 已切换为 /.5 和 *.5。
/*
* @param {Number} n - pass in any number
* @param {Number} scale - either pass in .5 or 1
*/
var superCoolRound = function(n,scale) {
return (Math.round(n / scale) * scale).toFixed(1);
};
回答by Thomas
I assume you want to format the number for output and not truncate the precision. In that case, use a DecimalFormat. For example:
我假设您想格式化输出数字而不是截断精度。在这种情况下，请使用 DecimalFormat。例如：
DecimalFormat df = new DecimalFormat("#.#");
df.format(rating);
