Ghost/ghost/admin/app/utils/ed-image-manager.js

const imageMarkdownRegex = /^!(?:\[([^\n\]]*)\])(?:\(([^\n\]]*)\))?$/gim;

// Process the markdown content and find all of the locations where there is an image markdown block
function parse(stringToParse) {
    let images = [];
    let m;

    while ((m = imageMarkdownRegex.exec(stringToParse)) !== null) {
        images.push(m);
    }

    return images;
}

// Figure out the start and end of the selection range for the src in the markdown, so we know what to replace
function getSrcRange(content, index) {
    let images = parse(content);
    let replacement = {};

    if (index > -1) {
        // [1] matches the alt text, and 2 matches the url between the ()
        // if the () are missing entirely, which is valid, [2] will be undefined and we'll need to treat this case
        // a little differently
        if (images[index][2] === undefined) {
            replacement.needsParens = true;
            replacement.start = content.indexOf(']', images[index].index) + 1;
            replacement.end = replacement.start;
        } else {
            replacement.start = content.indexOf('(', images[index].index) + 1;
            replacement.end = replacement.start + images[index][2].length;
        }
        return replacement;
    }

    return false;
}

export default {
    getSrcRange
};