Javascript 是否有任何JS函数来查找小数点前后的值
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/7881319/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Is there ay JS function to find value before and after decimal point
提问by user987880
I am validating a decimal number using JavaScript.
Am just using NaN
我正在使用 JavaScript 验证十进制数。我只是在使用NaN
var a = 12345.67 Is there any javascript function to get the count or the value itself before and after decimal point .
var a = 12345.67 是否有任何 javascript 函数来获取小数点前后的计数或值本身。
before() should return 1234
after() should return 67
Please dont suggest a substring!
请不要建议子字符串！
回答by John Hartsock
var a = 12345.67;
alert(a.toString().split(".")[0]); ///before
alert(a.toString().split(".")[1]); ///after
Here is a simple fiddle http://jsfiddle.net/qWtSc/
这是一个简单的小提琴http://jsfiddle.net/qWtSc/
zzzzBov's suggestion is this
zzzzBov 的建议是这个
Number.prototype.before = function () {
var value = parseInt(this.toString().split(".")[0], 10);//before
return value ? value : 0;
}
Number.prototype.after = function () {
var value = parseInt(this.toString().split(".")[1], 10);//after
return value ? value : 0;
}
Usage
用法
alert(a.before()); ///before
alert(a.after()); ///after
回答by Alex Wayne
beforeis easy. It's just a round down operation.
before简单。这只是一个舍入操作。
var before = function(n) {
return Math.floor(n);
};
afteris harder without string processing. I mean how would you handle after(Math.PI)? You can't hold a integer with an infinite number of digits after all.
after没有字符串处理更难。我的意思是你会怎么处理after(Math.PI)？毕竟你不能持有一个无限位数的整数。
But with some string processing it's easy, just know it won't be exact due to the wonders of floating point math.
但是通过一些字符串处理很容易，只要知道由于浮点数学的奇迹，它不会是精确的。
var after = function(n) {
var fraction = n.toString().split('.')[1];
return parseInt(fraction, 10);
};
回答by rlemon
Playing off of other answers... and you wanted a 'numeric' version.. still easiest to convert it to a string and work off the split function...
播放其他答案......你想要一个“数字”版本......仍然最容易将其转换为字符串并处理拆分功能......
function getNatural(num) {
return parseFloat(num.toString().split(".")[0]);
}
function getDecimal(num) {
return parseFloat(num.toString().split(".")[1]);
}
var a = 12345.67;
alert(getNatural(a)); ///before
alert(getDecimal(a)); ///after
回答by evilone
var decimalPlaces = 2;
var num = 12345.673
var roundedDecimal = num.toFixed(decimalPlaces);
var intPart = Math.floor(roundedDecimal);
var fracPart = parseInt((roundedDecimal - intPart), 10);
//or
var fractPart = (roundedDecimal - intPart) * Math.pow(10, decimalPlaces);
回答by T.Todua
To find the count/length of characters after dot:
要查找点后的字符数/长度：
var a = 12345.67;
var after_dot = (a.toString().split(".")[1]).length;
var before_dot= (a.toString().split(".")[0]).length;
回答by MaxArt
Unfortunately there's no way to get the factional part in a reliable way using math functions, because pretty odd roundings often occur, depending on the Javascript engine used. The best thing to do is to convert it to a string, and then checking if the results is in decimal or scientific notation.
不幸的是，没有办法使用数学函数以可靠的方式获得派系部分，因为经常发生非常奇怪的四舍五入，这取决于所使用的 Javascript 引擎。最好的办法是将其转换为字符串，然后检查结果是十进制还是科学记数法。
Number.prototype.after = function() {
var string = this.toString();
var epos = string.indexOf("e");
if (epos === -1) { // Decimal notation
var i = string.indexOf(".");
return i === -1 ? "" : n.substring(i + 1);
}
// Scientific notation
var exp = string.substring(epos + 1) - 0; // this is actually faster
// than parseInt in many browsers
var mantix = n.string.substring(0, epos).replace(".", "");
if (exp >= -1) return mantix.substring(exp + 1);
for (; exp < -1; exp++) mantix = "0" + mantix;
return mantix;
}
