Implement instance of

Dec 26, 2021#js79

AI Translation

This post is translated from Chinese into English through AI.View Original

AI-generated summary

The code snippet provided is a function called `instanceofFn` that is used to determine if a given constructor's prototype exists on a specific instance object. It does this by continuously traversing up the prototype chain until it finds the constructor's prototype or reaches the end of the chain. If the constructor's prototype is found, the function returns true; otherwise, it returns false.

First, instanceof is used to determine whether the prototype of a certain constructor exists on a certain instance object.

SmsClass instanceof Function ? "":SmsClass

Let's go straight to the code

export function instanceofFn(Left, Constructor) {
   const ConstructorP = Constructor.prototype;
   Left = Left.__proto__;
   // Keep looking up
   while (true) {
       if (Left === null) {
           return false;
       }
       if (Left === ConstructorP) {
           return true;
       }
       // Continue to search the prototype chain upwards
       Left = Left.__proto__;
   }
}