lodash some 方法性能为什么比 js 原生方法 还高？

根据 @vace 给出的 v8 源码。

// Executes the function once for each element present in the
// array until it finds one where callback returns true.
function ArraySome(f, receiver) {
  CHECK_OBJECT_COERCIBLE(this, "Array.prototype.some");
  // Pull out the length so that modifications to the length in the
  // loop will not affect the looping and side effects are visible.
  var array = ToObject(this);
  var length = TO_UINT32(array.length);
  if (!IS_SPEC_FUNCTION(f)) {
    throw MakeTypeError('called_non_callable', [ f ]);
  }
  var needs_wrapper = false;
  if (IS_NULL_OR_UNDEFINED(receiver)) {
    receiver = %GetDefaultReceiver(f) || receiver;
  } else {
    needs_wrapper = SHOULD_CREATE_WRAPPER(f, receiver);
  }
  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
  for (var i = 0; i < length; i++) {
    if (i in array) {
      var element = array[i];
      // Prepare break slots for debugger step in.
      if (stepping) %DebugPrepareStepInIfStepping(f);
      var new_receiver = needs_wrapper ? ToObject(receiver) : receiver;
      if (%_CallFunction(new_receiver, element, i, array, f)) return true;
    }
  }
  return false;
}

去掉里面的各种参数的类型检查，简化为以下代码后

function jsSome(array, receiver) { 
    let length = array.length;
    for (let i = 0; i < length; i++) {
        let element = array[i];
        if (receiver(element, i, array)) return true;
    }
    return false;
}

跑出来的成绩就和 lodash 几乎一致了。

这些类型检查我看了下，大部分对于底层泛用性来说是绝对必要的，但是对于确定的场景很多是不必要的。 所以对于 确定的场景 性能方面也不能盲目确信原生最佳。最针对的代码性能最优泛用性也最低。

完结撒花~