fake-input.js

const keyListener = (event) => {
    console.log(event.which);
    if (event.which === 13) {
        event.preventDefault();
    }
};

const changeListener = (event) => {
    requestAnimationFrame(() => {
        const element = event.target;

        if (element.innerText === "\n") {
            element.innerText = "";
        }
    })
};

Array.prototype.slice.call(document.querySelectorAll(".fake-input[contenteditable]")).forEach(elem => {
    elem.addEventListener("input", changeListener);
    if (!elem.dataset["multiline"]) {
        elem.addEventListener("keypress", keyListener);
    }
});