Using regex, extract values from a string in javascript

Question

Need to extract values from a string using regex(for perf reasons). Cases might be as follows:

RED,100
RED,"100"
RED,"100,"
RED,"100\"ABC\"200"

The resulting separated [label, value] array should be:

['RED','100']
['RED','100']
['RED','100,']
['RED','100"ABC"200']

I looked into solutions and a popular library even, just splits the entire string to get the values, e.g. 'RED,100'.split(/,/) might just do the thing.

But I was trying to make a regex with comma, which splits only if that comma is not enclosed within a quotes type value.

This isnt a standard CSV behaviour might be. But its very easy for end-user to enter values. enter label,value. Do whatever inside value, if thats surrounded by quotes. If you wanna contain quotes, use a backslash.

Any help is appreciated.

Yes take the case 3. If we split by comma, it will break in 3 piece right? which we dont want — Ayan
– Ayan, Commented Jan 18, 2018 at 15:22
From user`s point its simple entry. the format is label,value But if you want to enter comma(,) or quotes(") inside either label/value, we wont be splitting on that, — Ayan
– Ayan, Commented Jan 18, 2018 at 15:30

anubhava · Accepted Answer · 2018-01-18 15:35:14Z

1

You can use this regex that takes care of escaped quotes in string:

/"[^"\\]*(?:\\.[^"\\]*)*"|[^,"]+/g

RegEx Explanation:

": Match a literal opening quote
[^"\\]*: Match 0 or more of any character that is not \ and not a quote
(?:\\.[^"\\]*)*: Followed by escaped character and another non-quote, non-\. Match 0 or more of this combination to get through all escaped characters
": Match closing quote
|: OR (alternation)
[^,"]+: Match 1+ of non-quote, non-comma string

RegEx Demo

const regex = /"[^"\\]*(?:\\.[^"\\]*)*"|[^,"]+/g;

const arr = [`RED,100`, `RED,"100"`, `RED,"100,"`,
`RED,"100\\"ABC\\"200"`];
let m;

for (var i = 0; i < arr.length; i++) {
  var str = arr[i];
  var result = [];
  while ((m = regex.exec(str)) !== null) {
    result.push(m[0]);
  }
  console.log("Input:", str, ":: Result =>", result);
}

answered Jan 18, 2018 at 15:35

anubhava

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1 Comment

Ayan Over a year ago

Thanks a ton. This is incredible. Took almost 10mins to go by it. Thanks again. You just inspired me about the powers of regex.

Nina Scholz · Accepted Answer · 2018-01-18 15:36:57Z

1

You could use String#match and take only the groups.

var array = ['RED,100', 'RED,"100"', 'RED,"100,"', 'RED,"100\"ABC\"200"'];

console.log(array.map(s => s.match(/^([^,]+),(.*)$/).slice(1)))

answered Jan 18, 2018 at 15:36

Nina Scholz

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