Split a string according to flanking characters in javascript

Question

Javascript lets you split a string according to regular expression. Is it possible to use this functionality to split a string only when the delimiter is flanked by certain characters?

For example, if I want to split the string 12-93 but not at-13 using the - character? Is that possible?

Using a regular expression seems promising, but doing "12-93".split(/[0-9]-[0-9]/) yields ["1", "3"] because the flanking digits are considered to be part of the delimiter.

Can I specify the above split pattern (a dash preceded and followed by a digit) without chopping the flanking digits?

Other Examples

"55,966,575-165,162,787" should yield ["55,966,575", "165,162,787"]

"55,966,575x-165,162,787" should yield ["55,966,575x-165,162,787"]

"sdf55,966,575-165,162,787" should yield ["sdf55,966,575", "165,162,787"]

What about this: /d{2}-d{2}/ which specifies two digits a dash and two digits? — Scott Marcus
– Scott Marcus, Commented Nov 3, 2016 at 19:10

tmslnz · Accepted Answer · 2016-11-03 19:54:30Z

Using two adjacent character sets seems to work.

See example at https://regex101.com/r/uFHMW1/1

([0-9,a-z]+?[0-9]+)-([0-9]+[0-9,a-z]+)

Try this (live here https://repl.it/EOOQ/0 ):

var strings = [
"55,966,575-165,162,787",
"55,966,575x-165,162,787",
"sdf55,966,575-165,162,787",
];

var pattern = '^([0-9,a-z]+?[0-9]+)-([0-9]+[0-9,a-z]+)$';
var regex = new RegExp(pattern, 'i');

var matched = strings.map(function (string) {
	var matches = string.match( regex );
	if (matches) {
		return [matches[1], matches[2]];
	} else {
		return [string];
	}
});

console.log(matched)

You can also run the above expression as split() like:

string.split(re).filter( str => str.length )

where Array.filter() is used to get rid of the leading and trailing empty strings created when the RegExp matches your input.

var strings = [
"55,966,575-165,162,787",
"55,966,575x-165,162,787",
"sdf55,966,575-165,162,787",
];
var pattern = '^([0-9,a-z]+?[0-9]+)-([0-9]+[0-9,a-z]+)$';
var regex = new RegExp(pattern, 'i');

var matched = strings.map( string => string.split(regex).filter( str => str.length ) );

console.log(matched)

ppovoski · Accepted Answer · 2016-11-03 19:23:16Z

0

Try using a non-capturing lookahead. You are using a regex that captures all of the characters found, then uses that result as the split character(s).

answered Nov 3, 2016 at 19:23

ppovoski

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