Problems › JavaScript › text
Split one CSV line properly
An import job reads a CSV where some fields legitimately contain commas, so splitting on the comma alone corrupts the data.
- Commas separate fields, except inside a double-quoted field.
- Inside a quoted field, two double quotes in a row mean one literal quote.
- The quotes themselves are not part of the value.
- An empty line gives an empty list; an empty field between two commas gives an empty string.
parseCsvLine(line: string) → list<string>
Where you start
function parseCsvLine(line) {
}Worked examples
| Call | Result |
|---|---|
parseCsvLine("a,b,c") | ["a","b","c"] |
parseCsvLine("a,\"b,c\",d") | ["a","b,c","d"] |
parseCsvLine("\"say \"\"hi\"\"\",x") | ["say \"hi\"","x"] |
parseCsvLine("a,,b") | ["a","","b"] |
Hint
Walk the line one character at a time carrying a single boolean: are we inside quotes right now.
Reference solution in JavaScript
function parseCsvLine(line) {
if (line === '') return [];
const fields = [];
let cur = '', quoted = false, i = 0;
while (i < line.length) {
const c = line[i];
if (quoted) {
if (c === '"') {
if (line[i + 1] === '"') { cur += '"'; i += 2; continue; }
quoted = false; i++; continue;
}
cur += c; i++;
} else if (c === '"') { quoted = true; i++; }
else if (c === ',') { fields.push(cur); cur = ''; i++; }
else { cur += c; i++; }
}
fields.push(cur);
return fields;
}