Javascript 数组中的最小/最大日期？
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Min/Max of dates in an array?
提问by Legend
How can I find out the min and the max date from an array of dates? Currently, I am creating an array like this:
如何从日期数组中找出最小和最大日期？目前，我正在创建一个这样的数组：
var dates = [];
dates.push(new Date("2011/06/25"))
dates.push(new Date("2011/06/26"))
dates.push(new Date("2011/06/27"))
dates.push(new Date("2011/06/28"))
Is there a built-in function to do this or am I to write my own?
是否有内置函数来执行此操作，还是我自己编写？
回答by Andrew D.
Code is tested with IE,FF,Chrome and works properly:
代码经过 IE、FF、Chrome 测试并正常工作：
var dates=[];
dates.push(new Date("2011/06/25"))
dates.push(new Date("2011/06/26"))
dates.push(new Date("2011/06/27"))
dates.push(new Date("2011/06/28"))
var maxDate=new Date(Math.max.apply(null,dates));
var minDate=new Date(Math.min.apply(null,dates));
回答by Legend
Something like:
就像是：
var min = dates.reduce(function (a, b) { return a < b ? a : b; });
var max = dates.reduce(function (a, b) { return a > b ? a : b; });
Tested on Chrome 15.0.854.0 dev
在 Chrome 15.0.854.0 dev 上测试
回答by Mark Amery
_.minand _.maxwork on arrays of dates; use those if you're using Lodash or Underscore, and consider using Lodash (which provides many utility functions like these) if you're not already.
_.min并_.max处理日期数组；如果您正在使用 Lodash 或 Underscore，请使用它们，如果您还没有使用，请考虑使用 Lodash（它提供了许多类似的实用功能）。
For example,
例如，
_.min([
new Date('2015-05-08T00:07:19Z'),
new Date('2015-04-08T00:07:19Z'),
new Date('2015-06-08T00:07:19Z')
])
will return the second date in the array (because it is the earliest).
将返回数组中的第二个日期（因为它是最早的）。
回答by lvd
回答by Ricardo Tomasi
Since dates are converted to UNIX epoch (numbers), you can use Math.max/min to find those:
由于日期被转换为 UNIX 纪元（数字），您可以使用 Math.max/min 来查找那些：
var maxDate = Math.max.apply(null, dates)
// convert back to date object
maxDate = new Date(maxDate)
(tested in chrome only, but should work in most browsers)
（仅在 chrome 中测试，但应该在大多数浏览器中工作）
回答by Rudresh Ajgaonkar
**Use Spread Operators| ES6 **
**使用扩展运算符| ES6 **
let datesVar = [ 2017-10-26T03:37:10.876Z,
2017-10-27T03:37:10.876Z,
2017-10-23T03:37:10.876Z,
2015-10-23T03:37:10.876Z ]
Math.min(...datesVar);
That will give the minimum date from the array.
这将给出数组中的最小日期。
Its shorthand Math.min.apply(null, ArrayOfdates);
它的简写 Math.min.apply(null, ArrayOfdates);
回答by Kamil Kie?czewski
ONELINER:
单线：
var min= dates.sort((a,b)=>a-b)[0], max= dates.slice(-1)[0];
result in variables minand max, complexity O(nlogn), editable example here. If your array has no-date values (like null) first clean it by dates=dates.filter(d=> d instanceof Date);.
导致变量min和max，复杂度O(nlogn)，可编辑示例here。如果您的数组具有无日期值（如null），请先将其清理干净dates=dates.filter(d=> d instanceof Date);。
var dates = [];
dates.push(new Date("2011-06-25")); // I change "/" to "-" in "2011/06/25"
dates.push(new Date("2011-06-26")); // because conosle log write dates
dates.push(new Date("2011-06-27")); // using "-".
dates.push(new Date("2011-06-28"));
var min= dates.sort((a,b)=>a-b)[0], max= dates.slice(-1)[0];
console.log({min,max});回答by wong2
var max_date = dates.sort(function(d1, d2){
return d2-d1;
})[0];
回答by Samdeesh
The above answers do not handle blank/undefined values to fix this I used the below code and replaced blanks with NA :
上面的答案不处理空白/未定义的值来解决这个问题我使用了下面的代码并用 NA 替换了空白：
function getMax(dateArray, filler) {
filler= filler?filler:"";
if (!dateArray.length) {
return filler;
}
var max = "";
dateArray.forEach(function(date) {
if (date) {
var d = new Date(date);
if (max && d.valueOf()>max.valueOf()) {
max = d;
} else if (!max) {
max = d;
}
}
});
return max;
};
console.log(getMax([],"NA"));
console.log(getMax(datesArray,"NA"));
console.log(getMax(datesArray));
function getMin(dateArray, filler) {
filler = filler ? filler : "";
if (!dateArray.length) {
return filler;
}
var min = "";
dateArray.forEach(function(date) {
if (date) {
var d = new Date(date);
if (min && d.valueOf() < min.valueOf()) {
min = d;
} else if (!min) {
min = d;
}
}
});
return min;
}
console.log(getMin([], "NA"));
console.log(getMin(datesArray, "NA"));
console.log(getMin(datesArray));
I have added a plain javascript demo hereand used it as a filter with AngularJS in this codepen
回答by Samdeesh
This is a particularly great way to do this (you can get max of an array of objects using one of the object properties): Math.max.apply(Math,array.map(function(o){return o.y;}))
这是执行此操作的特别好方法（您可以使用对象属性之一获取对象数组的最大值）： Math.max.apply(Math,array.map(function(o){return o.y;}))
This is the accepted answer for this page: Finding the max value of an attribute in an array of objects
这是本页公认的答案： 在对象数组中查找属性的最大值
