Script to delete all reddit comments on the *current page* when viewing own comment history. Quick and dirty approach if you don't have more than a few hundred comments.

Deleting reddit comments.js

function deleteAllOnPage(comments, index) {
    var id = comments[index]
    if (!id) return
    console.debug('wiping ' + id)
    $.ajax({
        type: 'POST',
        url: '/api/editusertext',
        data: {
            thing_id: id,
            text: ' ',
            id: 'any',
            uh: r.config.modhash,
            renderstyle: 'html'
        },
        success: function successEdit() {
            console.debug('deleting ' + id)
            $.ajax({
                type: 'POST',
                url: '/api/del',
                data: {
                    executed: 'deleted',
                    id: id,
                    renderstyle: 'html',
                    uh: r.config.modhash
                },
                success: function successDel() {
                    deleteAllOnPage(comments, index + 1)
                },
                error: function errorDel() {
                    console.error('Failed to delete ' + id, arguments)
                }
            })
        },
        error: function errorEdit() {
            console.error('Failed to delete ' + id, arguments)
        }
    })
}

deleteAllOnPage($('.comment').map(function(){ return $(this).data('fullname') }), 0)

Unhiding everything on the page:

unhide_links = [...document.querySelectorAll('a[data-event-action=unhide]')]

automate = setInterval(() => { if (unhide_links.length) unhide_links.pop().click(); else clearInterval(automate); }, 1000)