Split a CSV with javascript

Question

Is there a way to split a CSV string with javascript where the separator can also occur as an escaped value. Other regex implementations solve this problem with a lookbehind, but since javascript does not support lookbehind I wonder how I could accomplish this in a neatly fashion using a regex expression.

A csv line might look like this

"This is\, a value",Hello,4,'This is also\, possible',true

This must be split into (strings containing)

[0] => "This is\, a value"
[1] => Hello
[2] => 4
[3] => 'This is also\, possible'
[4] => true

[Possible duplicate](http://stackoverflow.com/questions/1293147/javascript-code-to-parse-csv-data) — Guillaume Poussel, Oct 06 '13 at 10:56
Yes and no. I am explicitly looking for a clean regex that can solve my problem. — Rudolf, Oct 10 '13 at 08:29

score 1 · Accepted Answer · answered Oct 06 '13 at 11:14

1

Instead of trying to split you can try a global match for all that is not a , with this pattern:

/"[^"]+"|'[^']+'|[^,]+/g

answered Oct 06 '13 at 11:14

Casimir et Hippolyte

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Thank you Casimir. This will not work when you want to split the CSV line. But you are absolutely right, it does give the expected output. I could group this expression to get the result, but the end result will also include the comma. Personally I do find this solution a little bit better than (.*?[^\\])(,|$) since the result excludes the comma. – Rudolf Oct 10 '13 at 08:22

Darka · Answer 2 · 2013-10-06T11:29:06.753

0

for example you can use this regex:

(.*?[^\\])(,|$)

regex takes everything .*? until first comma, which does not have \ in front of it, or end of line

edited Oct 06 '13 at 11:29

answered Oct 06 '13 at 11:05

Darka

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Just a suggestion, if you add an explanation of what this regex does it will be more easier for OP to understand and use. – Harry Oct 06 '13 at 11:26
will do next time too. Thanks @Harry – Darka Oct 06 '13 at 11:29
Yes, this works, but the result does include the comma. If I split the CSV line with this regex I'm pretty close to the result. – Rudolf Oct 10 '13 at 08:20

score 0 · Answer 3 · answered Dec 04 '18 at 18:47

Here's some code that changes csv to json (assuming the first row it prop names). You can take the first part (array2d) and do other things with it very easily.

// split rows by \r\n.  Not sure if all csv has this, but mine did
const rows = rawCsvFile.split("\r\n");

// find all commas, or chunks of text in quotes.  If not in quotes, consider it a split point
const splitPointsRegex = /"(""|[^"])+?"|,/g;
const array2d = rows.map((row) => {
    let lastPoint = 0;
    const cols: string[] = [];
    let match: RegExpExecArray;
    while ((match = splitPointsRegex.exec(row)) !== null) {
        if (match[0] === ",") {
            cols.push(row.substring(lastPoint, match.index));
            lastPoint = match.index + 1;
        }
    }
    cols.push(row.slice(lastPoint));

    // remove leading commas, wrapping quotes, and unneeded \r
    return cols.map((datum) => 
        datum.replace(/^,?"?|"$/g, "")
        .replace(/""/g, `\"`)
        .replace(/\r/g, "")
    );
})

// assuming first row it props name, create an array of objects with prop names of the values given
const out = [];
const propsRow = array2d[0];
array2d.forEach((row, i) => {
    if (i === 0) { return; }
    const addMe: any = {};
    row.forEach((datum, j) => {
        let parsedData: any;
        if (isNaN(Number(datum)) === false) {
            parsedData = Number(datum);
        } else if (datum === "TRUE") {
            parsedData = true;
        } else if (datum === "FALSE") {
            parsedData = false;
        } else {
            parsedData = datum;
        }
        addMe[propsRow[j]] = parsedData;
    });
    out.push(addMe);
});

console.log(out);

score 0 · Answer 4 · answered Aug 08 '19 at 13:28

0

Unfortunately this doesn't work with Firefox, only in Chrome and Edge:

"abc\\,cde,efg".split(/(?<!\\),/) will result in ["abc\,cde", "efg"].

You will need to remove all (unescaped) escapes in a second step.

answered Aug 08 '19 at 13:28

Brixomatic

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Split a CSV with javascript

4 Answers4