locutus/tcl/string/first.js

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

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.first = first;
function first(needle, haystack, startIndex) {
    //      discuss at: https://locutus.io/tcl/first/
    // parity verified: Tcl 8.6
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //       example 1: first('or', 'Hello World')
    //       returns 1: 7
    //       example 2: first('x', 'Hello World')
    //       returns 2: -1
    //       example 3: first('', 'abc', 2)
    //       returns 3: -1
    const source = String(haystack);
    const search = String(needle);
    const offset = startIndex === undefined ? 0 : Math.max(0, Math.trunc(Number(startIndex)));
    if (search === '') {
        return -1;
    }
    return source.indexOf(search, offset);
}