if (!Array.prototype.findIndex) {
  Array.prototype.findIndex = function(predicate) {
    "use strict"
    if (this == null) {
      throw new TypeError(
        "Array.prototype.findIndex called on null or undefined"
      )
    }
    if (typeof predicate !== "function") {
      throw new TypeError("predicate must be a function")
    }
    var list = Object(this)
    var length = list.length >>> 0
    var thisArg = arguments[1]
    var value

    for (var i = 0; i < length; i++) {
      value = list[i]
      if (predicate.call(thisArg, value, i, list)) {
        return i
      }
    }
    return -1
  }
}