使用`new Date`解析日期字符串时出错 [英] Error parsing date string with `new Date`

问题描述

datefromJSON = req.body.occasion_date;
occasion_date = new Date(datefromJSON);
console.log(occasion_date);

//while running this i get log like this 
//"Invalid Date"

当我从req.body获取json数据然后保存在datefromJSON var中，并且存储到数据库中我用来转换为Date对象获取错误

when i get json data from req.body then save in datefromJSON var, and for storing into database i use to convert into Date object that get error

推荐答案

您的日期字符串（无论是 31-08-2016）不是以 Date 构造函数识别的格式。所以你最终得到了一个 Date ，其基础时间值是 NaN ，当你显示为无效日期时请求字符串版本。无条件的例子：

Your date string (whatever it is "31-08-2016") isn't in a format recognized by the Date constructor. So you ended up with a Date whose underlying time value is NaN, which is shown as "Invalid Date" when you ask for the string version. Gratuitous example:

console.log(new Date("foobar").toString());

仅格式规范要求支持的JavaScript实现是在2009年的ES5规范中添加的，实际上是（并且ES2015实际上是ES5中的错误）ISO-8601的子集。例如：

The only format the specification requires a JavaScript implementation to support is the one added in the ES5 specification in 2009, which was meant to be (and as of ES2015 actually is; there was an error in ES5) a subset of ISO-8601. So for instance:

console.log(new Date("2016-08-31T09:25").toString());

每一个我已经遇到的JavaScript实现非正式支持使用斜杠解析US格式， MM / dd / yyyy ，（即使在非美国语言环境中） ），但时区各不相同（大部分都将其解释为当地时间，其他时间则按GMT解释）。

Every JavaScript implementation I've run into also unofficially supports parsing the U.S. format with slashes, MM/dd/yyyy, (even in non-U.S. locales), but the timezone varies (most interpret it as local time, others interpret it in GMT).

所以你需要：

• 解析你的字符串（正则表达式， split 等）并使用表格日期支持单独提供部件的构造函数。请注意月份值从0 = 1月开始（不是1 = 1月）。有几十个问题，这里有关于SO的例子。以下是将常见的'dd-MM-yyyy HH：mm：ss 或'dd-MM-yyyy HH：mm：ss.SSS 格式解析为本地日期的示例/时间：

• Parse your string (regular expressions, split, etc.) and use the form of the Date constructor that supports supplying the parts individually. Mind the gotcha that the months value starts with 0 = January (not 1 = January). There are several dozen questions with examples of that here on SO. Here's an example of parsing the common 'dd-MM-yyyy HH:mm:ssor 'dd-MM-yyyy HH:mm:ss.SSS format as a local date/time:

基于正则表达式：

function parseIt(str) {
  var rex = /^\s*(\d{1,2})[\/-](\d{1,2})[\/-](\d{4})(?: (\d{1,2})(?::(\d{1,2})(?::(\d{1,2})(?:\.(\d{1,3}))?)?)?)?\s*$/;
  var parts = rex.exec(str);
  var dt = null;
  if (parts) {
    dt = new Date(+parts[3], // Year
      +parts[2] - 1, // Month
      +parts[1], // Day
      +parts[4] || 0, // Hours
      +parts[5] || 0, // Minutes
      +parts[6] || 0, // Seconds
      +parts[7] || 0 // Milliseconds
    );
  }
  return dt;
}

function test(str) {
  var dt = parseIt(str);
  console.log(str, "=>");
  console.log("   " + String(dt));
  console.log("   (" + (dt ? dt.toISOString() : "null") + ")");
}

test("foobar");
test("31-08-2016");
test("31/08/2016");
test("31/08/2016 9");
test("31/08/2016 9:25");
test("31/08/2016 09:25");
test("31/08/2016 09:25:17");
test("31/08/2016 09:25:17.342");

正则表达式看起来很复杂，但它实际上只是嵌套在非捕获，可选组内的一堆捕获组。 此处的解释。

• 使用库（如 MomentJS ），可以通过说明格式是什么来解析字符串。

• Use a library (like MomentJS) that lets you parse a string by saying what the format is.

这篇关于使用`new Date`解析日期字符串时出错的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！