Splitting A String Using A Javascript Regex But Keeping The Delimiter?

I'm receiving input like: F12T213B1239T2F13T341F324 and I have to group it by letter followed by the numbers that follows it. So the ideal output would be: F12,T213,B1239,T2,F13,T

Solution 1:

var str = "F12T213B1239T2F13T341F324";
var regex = /(?=T)|(?=F)|(?=B)/g;
console.log(str.split(regex));

Solution is based on Positive lookahead

Solution 2:

One way to do this is to replace all the FTBs with a space followed by that letter:

regex: [FTB]
replacement:  $0// note the leading space

Then, you can split it with space characters.

Solution 3:

You can do it with a noncapturing group and some empty value filtering.

The regex is : ((?:F|T|B)\d+)

Here's a working code:

console.log(
    "F12T213B1239T2F13T341F324"
        .split(/((?:F|T|B)\d+)/g)
        .filter(d => d != "")
);

Solution 4:

Instead of using .split() you can use .match() with a matching group in the regex, it will give you an array of all your wanted matches.

This is the regex you need /([TBF]\d{1,4})/g.

This is how should be your code:

var input = "F12T213B1239T2F13T341F324";
var separators = ['T', 'B', 'F'];
var parts = input.match(newRegExp('(['+separators.join('')+']\\d{1,4})','g'));

console.log(parts);

Note:

• The ['+separators.join('')+'] will give you the following [TBF], in your regex so it matches one of the separators.
• And \d{1,4} will match the digits following that separator.

Demo:

var input = "F12T213B1239T2F13T341F324";
var separators = ['T', 'B', 'F'];
var parts = input.match(newRegExp('(['+separators.join('')+']\\d{1,4})','g'));

console.log(parts);