locutus/esm/golang/path/Ext.js

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

export function Ext(path) {
    //      discuss at: https://locutus.io/golang/path/Ext
    // parity verified: Go 1.23
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //       example 1: Ext('/a/b/c.txt')
    //       returns 1: '.txt'
    //       example 2: Ext('/a/b.tar.gz')
    //       returns 2: '.gz'
    //       example 3: Ext('/a/b')
    //       returns 3: ''
    //       example 4: Ext('.profile')
    //       returns 4: '.profile'
    const raw = String(path);
    let end = raw.length;
    while (end > 0 && raw[end - 1] === '/') {
        end -= 1;
    }
    if (end === 0) {
        return '';
    }
    const trimmed = raw.slice(0, end);
    const slash = trimmed.lastIndexOf('/');
    const base = trimmed.slice(slash + 1);
    const dot = base.lastIndexOf('.');
    if (dot < 0) {
        return '';
    }
    return base.slice(dot);
}