Avoid unnecesary prototype loop

[WebReflection]

Background

People at redux-toolkit copy/pasted this utility in there, and they are not welcoming a PR because of that, but the while loop in here is completely unnecessary, as the comparison is made on the first proto only.

Improvements

• O(1) instead of O(n)
• safe fallback for Object.create(null) cases
• fast lane for new Class() derived objects
• better performance
• smaller code size

As this change has zero downsides, unless I am missing some explicit reason to while loop instead of never using getPrototypeOf more than twice, I hope it'll get in, so that others might copy and paste this new version.

Best Regards.

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[timdorr]

Same reasoning here as your linked PR. You can read the background in #2599.

[WebReflection]

If ever interested in actually improving this little part of the equation, I've fixed all Travis CI related issues. It would've picked 'em up if not closed.

/**
 * @param obj The object to inspect.
 * @returns True if the argument appears to be a plain object.
 */
export default function isPlainObject(obj: any): boolean {
  return (
    typeof obj === 'object' &&
    obj !== null &&
    Object.getPrototypeOf(Object.getPrototypeOf(obj) || {}) === null
  )
}

Best Regards.