Type Alias SplitCSVFields<Char, Delimiter, Quotation, Escaping, Col, Result>

SplitCSVFields: Char extends `${Delimiter}${infer R}`
    ? Escaping extends true
        ? SplitCSVFields<
            R,
            Delimiter,
            Quotation,
            true,
            `${Col}${Delimiter}`,
            Result,
        >
        : SplitCSVFields<R, Delimiter, Quotation, false, "", [...Result, Col]>
    : Char extends `${Quotation}${infer R}`
        ? Escaping extends true
            ? R extends ""
            | Delimiter
            | `${Delimiter}${string}`
                ? SplitCSVFields<R, Delimiter, Quotation, false, Col, Result>
                : SplitCSVFields<
                    R,
                    Delimiter,
                    Quotation,
                    true,
                    `${Col}${Quotation}`,
                    Result,
                >
            : SplitCSVFields<R, Delimiter, Quotation, true, Col, Result>
        : Char extends `${infer F}${infer R}`
            ? SplitCSVFields<
                R,
                Delimiter,
                Quotation,
                Escaping,
                `${Col}${F}`,
                Result,
            >
            : [...Result, Col] extends [""]
                ? readonly string[]
                : readonly [...Result, Col]

Split CSV-formatted string into field array with proper unescaping.

Type Parameters

Char extends string
Delimiter extends string = DEFAULT_DELIMITER
Quotation extends string = DEFAULT_QUOTATION
Escaping extends boolean = false
Col extends string = ""
Result extends string[] = []

Remarks

This type handles CSV-specific parsing:

Unquotes quoted fields
Handles escaped quotation marks
Splits by the specified delimiter

Example: Default

const header = `name,age,city,zip`;

type _ = SplitCSVFields<typeof header>
// ["name", "age", "city", "zip"]

Example: With different delimiter and quotation

const header = `name@$a
ge$@city@zip`;

type _ = SplitCSVFields<typeof header, "@", "$">
// ["name", "a\nge", "city", "zip"]