OOP - JavaScript 挑战

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oop 相关挑战

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实例化

/**
 * @param {any} obj
 * @param {target} target
 * @return {boolean}
 */

// one-line solution
function myinstanceof(obj, fn) {
  return fn.prototype.isprototypeof(obj);
}

function myinstanceof(obj, fn) {
  if (typeof obj !== "object" || obj === null) {
    return false;
  }

  if (typeof fn !== "function") {
    return false;
  }

  let proto = object.getprototypeof(obj);

  while (proto) {
    if (proto === fn.prototype) {
      return true;
    }

    proto = object.getprototypeof(proto);
  }

  return false;
}

// usage example
class a {}
class b extends a {}
const b = new b();
console.log(myinstanceof(b, b)); // => true
console.log(myinstanceof(b, a)); // => true
console.log(myinstanceof(b, object)); // => true
function c() {}
console.log(myinstanceof(b, c)); // => false
c.prototype = b.prototype;
console.log(myinstanceof(b, c)); // => true
c.prototype = {};
console.log(myinstanceof(b, c)); // => false

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新的

/**
 * @param {Function} constructor
 * @param {any[]} args
 * `myNew(constructor, ...args)` should return the same as `new constructor(...args)`
 */

function myNew(constructor, ...args) {
  const obj = {};
  Object.setPrototypeOf(obj, constructor.prototype);

  const result = constructor.call(obj, ...args);

  if (typeof result !== "object" || result == null) {
    return obj;
  } else {
    return result;
  }
}

// Usage example
function Person(name) {
  this.name = name;
}
const person = myNew(Person, "Mike");
console.log(person); // => Person { name: 'Mike' }

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参考

• 60。创建您自己的新运算符 - bfe.dev
• 90。编写你自己的实例 - bfe.dev
• 实例 - mdn
• 新 - mdn
• 方法链 - wikipedia.org
• 2726。带方法链的计算器 - leetcode

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