$string = 'https://www.youtube.com/watch?v=jlr3w0MS0k8';
echo str_replace('watch?v=', 'v/', $string);

let colors = {
  'orange': 'rgb(255, 165, 0)',
  'blue': 'rgb(0, 0, 255)'
}, buttons = document.getElementsByClassName('btn'), buttonListener = (e) => {
  let currentColor = e.srcElement.innerHTML, circles = document.getElementsByClassName('c');
  
  for(let i = 0; i < circles.length; i += 1) {
    let currentCircle = circles[i];
    
    if(!currentCircle.style['background-color'] || currentCircle.style['background-color'] != colors[currentColor]) {
      currentCircle.style['background-color'] = colors[currentColor];
      break;
    } else continue;
    
  }
  
};

Array.from(buttons, btn => btn.addEventListener('click', buttonListener));

$v->api('wall.post', array(
    'owner_id' => 1, // wall id. < 0 - communities.
    'message' => 'Тест'
));