实例相等性检查返回false？

Question

我已经在JavaScript中使用构造函数和一些方法创建了一个简单的Vector类。 add方法返回一个新的Vector实例。将add方法的返回值与用相同值声明的新实例进行比较时，将返回false。我也尝试过将相等运算符更改为double equals，因此我认为问题与引用无关。

class Vector {
  constructor(components) {
    this.length = components.length;
    this.contents = components;
  }

  add(vector) {
    if (this.length === vector.length) {
      let a = [];
      this.contents.forEach((cur, index) =>
        a.push(cur + vector.contents[index])
      );
      return new Vector(a);
    }
    throw Error;
  }

  subtract(vector) {
    if (this.length === vector.length) {
      let a = [];
      this.contents.forEach((cur, index) =>
        a.push(cur - vector.contents[index])
      );
      return new Vector(a);
    }
    throw Error;
  }

  dot(vector) {
    return this.contents.reduce(
      (acc, cur, index) => (acc += cur * vector.contents[index]),
      0
    );
  }

  norm() {
    return this.contents.reduce((acc, cur) => (acc += Math.pow(cur, 2)), 0);
  }

  equals(vector) {
    return this.contents === vector;
  }
  toString() {
    return this.contents.toString();
  }
}

let a = new Vector([10, 20, 30]);
let b = new Vector([5, 15, 25]);

console.log(new Vector([15, 35, 55]));
console.log(a.add(b));

//Why does the log below return false?
console.log(new Vector([15, 35, 55]) === a.add(b));

Answer 1

[使用===比较数组时，您正在比较它们的地址。签出：

> a = [1,2]
[ 1, 2 ]
> b = [1,2]
[ 1, 2 ]
> a === b
false

如果数组包含相同的元素，则需要迭代。

顺便说一句，您还应该写throw **new** Error()。