Question

I'm trying to do something I don't remember/find if it is possible in javascript.

I have an object constructor "Point" and I want to know if it possible to, for example, sum two different objects like bellow.

function Point(x, y) {
    this.x = x;
    this.y = y;
}

a = new Point(1,2);
b = new Point(2,3);
c = a+b;


console.log('a: ', a)
console.log('b: ', b)
console.log('c: ', c)

a = Point {x: 1, y: 2}
b = Point {x: 2, y: 3}
Expected result: c = Point {x: 3, y: 5}

Answer 1

您可以为此创建一个函数。应该接受两个点的函数就足够了，然后在实现中创建一个包含每个属性之和的新Point。

function addPoint(pointA, pointB) {
 const newX = pointA.x + pointB.x;
 const newY = pointA.y + pointB.y;
 return new Point(newX, newY);
}

这是您可以执行的最基本的代码，但是例如，还有其他方法，例如允许多个参数，然后为所有参数生成总和，也将需要另一种方法。

Answer 2

function sumOfObjects(Obj1, Obj2){
    var finalObj = {};
    this.keys(Obj1).forEach(value =>{
        if (Obj2.hasOwnProperty(value)) {
            finalObj[value] = Obj1[value] + Obj2[value]
        }  
    });
    return finalObj;
 }

Answer 3

您可以执行以下代码。我们在Point函数上添加了一个静态方法，该方法将添加两个对象并返回新对象。

function Point(x, y) {
    this.x = x;
    this.y = y;
}

Point.add = function(a, b) {
    const x = a.x + b.x;
    const y = a.y + b.y;
    return new Point(x, y)
}

a = new Point(1,2);
b = new Point(2,3);
c = Point.add(a, b)


console.log('a: ', a)
console.log('b: ', b)
console.log('c: ', c)

Answer 4

因此，事实证明这是可行的。只是不建议这样做。

在对旧帖子Fake operator overloading in JavaScript article和git Fake operator overloading for JavaScript code进行了进一步的挖掘之后，我找到了解决方案

致谢作者Axel Rauschmayer

function Point(x, y) {
  if (arguments.length === 0) {
    x = 0;
    y = 0;
  } else if (arguments.length !== 2) {
    throw new Error("Need either 0 or 2 arguments");
  }
  this.x = x;
  this.y = y;
}

//-------------- Operator overloading
Point.operands = [];

Point.prototype.valueOf = function() {
  Point.operands.push(this);
  // Lowest natural number x where the following are all different:
  // x + x, x - x, x * x, x / x
  return 3;
}
Object.defineProperty(Point.prototype, "_", {
  set: function(value) {
    var ops = Point.operands;
    var operator;
    if (ops.length >= 2 && (value === 3 * ops.length)) {
      operator = this.setAdd;
    } else {
      throw new Error("Unsupported operation (code " + value + ")");
    }
    Point.operands = []; // reset
    return operator.apply(this, ops);
  },
  get: function() {
    return this.toString();
  }
});

//-------------- Operator implementations
Point.prototype.setAdd = function(first) {
  this.x = first.x;
  this.y = first.y;
  [].slice.call(arguments, 1).forEach(function(op) {
    this.x += op.x;
    this.y += op.y;
  }, this);
  return this;
}

//-------------- Various helpers
Point.prototype.toString = function() {
  return "Point(" + this.x + ", " + this.y + ")";
}
Point.prototype.equals = function(other) {
  return this.x === other.x && this.y === other.y;
}

//-------------- Testing it
var p = new Point();
var a = new Point(1, 2);
var b = new Point(4, 3);

p._ = a + b;
console.log(p); // Point {x: 5, y: 5}

Answer 5

您可能不只是使用+运算符。在javascript中，如果对象位于AdditiveExpression中，则它将转换为原始值（字符串或数字）。

因此，没有一种干净的方法可以对javascript中两个对象的属性求和，您可能需要创建一个附加函数。

How to sum properties of two objects in javascript

5 个答案: