What is the best way to use regular expressions in JavaScript to pull out a date value from a string?

Question

What is the best way to use regular expressions in JavaScript to pull out a date value from a string?

I am working with a string in this format:

var value = "/Date(1454187600000+0300)/"

. From this, I need to extract a date format like 1/30/2016. Currently, I have the following code snippet:

var value = "/Date(1454187600000+0300)/"; // I need to extract from here.
var nd = new Date(1454187600000); //this is static.
var month = nd.getUTCMonth() + 1; //months ranging from 1-12
var day = nd.getUTCDate();
var year = nd.getUTCFullYear();
newdate = month + "/" + day + "/" + year;
console.log( newdate ); //works fine

However, I am unsure of how to use regular expressions to fetch the numbers from the value variable. Can anyone provide some guidance on this?

javascript regex

Answer 1

Answer №1

If you're searching for the specific date section, a capture group can be used to extract it:

nd = new Date(value.match(/\/Date\((\d+)/)[1] * 1);
//=> Sat Jan 30 2016 16:00:00 GMT-0500 (EST)

The expression /\/Date\((\d+)/)[1] will retrieve "1454187600000", and multiplying it by 1 will convert it into an integer.

Answer 2

If you're searching for the specific date section, a capture group can be used to extract it:

nd = new Date(value.match(/\/Date\((\d+)/)[1] * 1);
//=> Sat Jan 30 2016 16:00:00 GMT-0500 (EST)

The expression /\/Date\((\d+)/)[1] will retrieve "1454187600000", and multiplying it by 1 will convert it into an integer.

Answer 3

Answer №2

One way to obtain the number from the given string is by using the split method instead of regex. For instance, in the string "/Date(1454187600000+0300)/", you can achieve this by splitting the string at the '+' character and then at the '(' character like so: "/Date(1454187600000+0300)/".split('+')[0],split('(')[1]

Answer 4

One way to obtain the number from the given string is by using the split method instead of regex. For instance, in the string "/Date(1454187600000+0300)/", you can achieve this by splitting the string at the '+' character and then at the '(' character like so: "/Date(1454187600000+0300)/".split('+')[0],split('(')[1]

Answer 5

Answer №3

To acquire the necessary data from a string (which can be converted to numbers), you must use pairs of capture groups. After extracting these groups, it is crucial to adjust the number to accommodate the timezone before feeding it into new Date. This adjustment process becomes simpler with additional captures. Below are detailed steps on how to achieve this:

var value = "/Date(1454187600000+0300)/";
// Extract required parts
var parts = /^\/Date\((\d+)([-+])(\d{2})(\d{2})\)\/$/.exec(value);
// Acquire time as a number (milliseconds since The Epoch)
var time = +parts[1];
// Obtain offset in milliseconds
var offset = (+parts[3] * 3600 + +parts[4] * 60) * 1000;
// Apply the necessary adjustment according to timezone
if (parts[2] == "+") {
  // For a `+` timezone meaning ahead of UTC, subtracting the offset gives UTC
  time -= offset;
} else {
  // If timezone is `-`, behind UTC, adding the offset results in UTC
  time += offset;
}
// Generate the date object
var dt = new Date(time);
document.body.innerHTML = dt.toISOString();

The regex pattern

/^\/Date\((\d+)([-+])(\d{2})(\d{2})\)\/$/

breakdown is as follows:

^ - Denotes start of input
\/ - Represents a literal /
Date - Indicates the verbatim text Date
\( - Stands for a literal (
(\d+) - Capture group for one or more digits; pertaining to the larger number segment
([-+]) - Capture group indicating the sign of offset, either - or +
(\d{2}) - Capture group for precisely two digits representing hours in the offset
(\d{2}) - Additional capture group for two digits portraying minutes within the offset
\) - Marks a literal )
\/ - Shows a literal /
$ - Signifies end of input

Detailed explanation on regex101

Answer 6

To acquire the necessary data from a string (which can be converted to numbers), you must use pairs of capture groups. After extracting these groups, it is crucial to adjust the number to accommodate the timezone before feeding it into new Date. This adjustment process becomes simpler with additional captures. Below are detailed steps on how to achieve this:

var value = "/Date(1454187600000+0300)/";
// Extract required parts
var parts = /^\/Date\((\d+)([-+])(\d{2})(\d{2})\)\/$/.exec(value);
// Acquire time as a number (milliseconds since The Epoch)
var time = +parts[1];
// Obtain offset in milliseconds
var offset = (+parts[3] * 3600 + +parts[4] * 60) * 1000;
// Apply the necessary adjustment according to timezone
if (parts[2] == "+") {
  // For a `+` timezone meaning ahead of UTC, subtracting the offset gives UTC
  time -= offset;
} else {
  // If timezone is `-`, behind UTC, adding the offset results in UTC
  time += offset;
}
// Generate the date object
var dt = new Date(time);
document.body.innerHTML = dt.toISOString();

The regex pattern

/^\/Date\((\d+)([-+])(\d{2})(\d{2})\)\/$/

breakdown is as follows:

^ - Denotes start of input
\/ - Represents a literal /
Date - Indicates the verbatim text Date
\( - Stands for a literal (
(\d+) - Capture group for one or more digits; pertaining to the larger number segment
([-+]) - Capture group indicating the sign of offset, either - or +
(\d{2}) - Capture group for precisely two digits representing hours in the offset
(\d{2}) - Additional capture group for two digits portraying minutes within the offset
\) - Marks a literal )
\/ - Shows a literal /
$ - Signifies end of input

Detailed explanation on regex101

What is the best way to use regular expressions in JavaScript to pull out a date value from a string?

Answer №1

Answer №2

Answer №3

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