jfa-go/ts/modules/stripmd.ts

const removeMd = require("remove-markdown");

function stripAltText(md: string): string {
    let altStart = -1; // Start of alt text (between '[' & ']')
    let urlStart = -1; // Start of url (between '(' & ')')
    let urlEnd = -1;
    let prevURLEnd = -2;
    let out = "";
    for (let i = 0; i < md.length; i++) {
        if (altStart != -1 && urlStart != -1 && md.charAt(i) == ")") {
            urlEnd = i - 1;
            out += md.substring(prevURLEnd + 2, altStart - 1) + md.substring(urlStart, urlEnd + 1);
            prevURLEnd = urlEnd;
            altStart = -1;
            urlStart = -1;
            urlEnd = -1;
            continue;
        }
        if (md.charAt(i) == "[" && altStart == -1) {
            altStart = i + 1;
            if (i > 0 && md.charAt(i - 1) == "!") {
                altStart--;
            }
        }
        if (i > 0 && md.charAt(i - 1) == "]" && md.charAt(i) == "(" && urlStart == -1) {
            urlStart = i + 1;
        }
    }
    if (prevURLEnd + 1 != md.length - 1) {
        out += md.substring(prevURLEnd + 2);
    }
    if (out == "") {
        return md;
    }
    return out;
}

export function stripMarkdown(md: string): string {
    return removeMd(stripAltText(md));
}