locutus/esm/r/base/match.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

export function match(value, table, nomatch = null) {
    //  discuss at: https://locutus.io/r/match/
    // original by: Kevin van Zonneveld (https://kvz.io)
    //      note 1: Returns the first 1-based match position, similar to R match.
    //      note 2: Returns nomatch when provided, otherwise null.
    //   example 1: match('b', ['a', 'b', 'c'])
    //   returns 1: 2
    //   example 2: match('z', ['a', 'b', 'c'])
    //   returns 2: null
    //   example 3: match(3, [1, 2, 3, 2], 0)
    //   returns 3: 3
    if (!Array.isArray(table)) {
        return nomatch;
    }
    for (let i = 0; i < table.length; i++) {
        if (Object.is(table[i], value)) {
            return i + 1;
        }
    }
    return nomatch;
}