Function isValidArrayIndex

m3u8/vue.js:79–82

* Check if val is a valid array index.

(val)

   * Check if val is a valid array index.
   */
  function isValidArrayIndex (val) {
    var n = parseFloat(String(val));
    return n >= 0 && Math.floor(n) === n && isFinite(val)
  }

  function isPromise (val) {
    return (