const element = document.getElementsByClassName('im-chat-input--text')[0];

element.onkeyup = () => {
    if (element.getValue().indexOf('-') !== -1) {
        element.setValue(element.getValue().replace(/-/g, '—'))

        const range = document.createRange();
        range.selectNodeContents(element);
        range.collapse(false);
        const sel = window.getSelection();
        sel.removeAllRanges();
        sel.addRange(range);
    }
}