如何使用javascript从字符串中提取日期

Question

How does one extract a date from a string using javascript? It can be in the following formats:

31.07.2014

07.31.2014

2014.07.31 the same format but divided by spaces or / or - 31 07 2014 31/07/2014 31-07-2014

the string may contain other character like

Teen.Wolf.S04E06.Orphaned.28.07.2014.HDTV

so how to extract date from these type of name.

I thought of first extracting all the numbers and then comparing if it is greater than 12 to make sure it is month or date. I don't know much about regEx (Regular Expressions) so if it is used please explain a little thank you

Answer 1

probably use a regex like

/(\d{4}([.\-/ ])\d{2}\2\d{2}|\d{2}([.\-/ ])\d{2}\3\d{4})/

\d - a digit (equivilant to character class [0-9]
{n} - match n characters
[.\-/ ] - character class matches a single . - / or space (- needs to be escaped because it indicates a range in a character class
\n - a backreference matches the nth match so / will match another / and not a -, /, space or .

you can pull out the first part of the regex and inspect it, it is the same as the second part, except the 4 digits and 2 digits have been swapped

/\d{4}([.\-/ ])\d{2}\1\d{2}/

Answer 2

Maybe this could help you ( Demo Fiddle here ):

function getDate(d)
{
    var day, month, year;

    result = d.match("[0-9]{2}([\-/ \.])[0-9]{2}[\-/ \.][0-9]{4}");
    if(null != result) {
        dateSplitted = result[0].split(result[1]);
        day = dateSplitted[0];
        month = dateSplitted[1];
        year = dateSplitted[2];
    }
    result = d.match("[0-9]{4}([\-/ \.])[0-9]{2}[\-/ \.][0-9]{2}");
    if(null != result) {
        dateSplitted = result[0].split(result[1]);
        day = dateSplitted[2];
        month = dateSplitted[1];
        year = dateSplitted[0];
    }

    if(month>12) {
        aux = day;
        day = month;
        month = aux;
    }

    return year+"/"+month+"/"+day;
}

Answer 3

RegEX will help you to extract date with Different Type of format and It returns as Array,

let str="dd/mm/yyyy06/06/2018 yyyy/mm/dd 2018/02/12 d/m/yy 1/1/18 dd/mm/yy 18/12/12 mm/d/yyyy 12/2/2018 m/dd/yyyy 1/12/2018 yy/m/d 18/1/1 yy/mm/d 18/12/1 yyyy/2018/1/1";
str.match(/(\d{1,4}([.\-/])\d{1,2}([.\-/])\d{1,4})/g);

Reference Link From regextester

Answer 4

I think you can use regex for this. The main three expressions that you need are the following:

[0-9]{4} // year
(0[1-9]|1[0-2]) // month
(0[1-9]|[1-2][0-9]|3[0-1]) // day

You can combine these to fit the formats you mentioned, for example, to match "31.07.2014":

(0[1-9]|[1-2][0-9]|3[0-1])\.(0[1-9]|1[0-2])\.[0-9]{4}

Or "31/07/2014":

(0[1-9]|[1-2][0-9]|3[0-1])\/(0[1-9]|1[0-2])\/[0-9]{4}

You can decide which formats you need and create one regex expression separating the formats with the OR operator |.

Answer 5

function myFunction() {
    var str = "Teen.Wolf.Orphaned.28.07.2014.HDTV";
    var res = str.split(".");


    var text = "";
    var x;
    for (x in res) {
        if (!isNaN(res[x])) {
            text += res[x];
            if (text.length == 2) { text += ','} 
            else if (text.length == 5) { text += ',' } 
        }
    }

    document.write(text);
}

This will write "28,07,2014"

NOTE: only use this way if the strings will always be in a format similar to the ones you posted above.