options-firefox.js

'use strict';
/* global browser */
var commands = [];
var shortcuts = document.getElementById('shortcuts');

function commandsUpdate() {
  commands.forEach(async command => {
    const id = command.name + 'shortcut';
    const element = document.getElementById(id);
    if (element.value !== command.shortcut) {
      try {
        await browser.commands.update({
          name: command.name,
          shortcut: element.value
        });
      } catch {
        alert('Invalid shortcut used.');
      }
      getCommands();
    }
  });
}

window.addEventListener('keyup', event => {
  if (event.keyCode === 13) {
    event.preventDefault();
    commandsUpdate();
  }
});

getCommands();

async function getCommands() {
  commands = await browser.commands.getAll();
  commands.forEach(command => {
    const id = command.name + 'shortcut';
    const element = document.getElementById(id);
    if (element) {
      element.value = command.shortcut;
      return
    }
    const label = document.createElement('label');
    label.innerText = command.description + ' ';
    label.setAttribute('for', id);
    const input = document.createElement('input');
    input.type = 'text'
    input.id = id;
    input.value = command.shortcut;
    label.appendChild(input);
    shortcuts.appendChild(label);
    const br = document.createElement('br');
    shortcuts.appendChild(br);
  });
};