面向对象的编程新体验：JS对象分类带你领略代码之美

2023-11-08 03:57:40

JS对象分类的魅力
在面向对象编程中，对象是程序的基本单位，它将数据和方法组合在一起，以简化程序的开发和维护。JS对象分类提供了将对象组织成类别并定义它们之间关系的有效方式，使其更加易于管理和理解。

案例1：写一个正方形程序

function Square(side) {
  this.side = side;
}
Square.prototype.area = function() {
  return this.side * this.side;
};
const square = new Square(5);
console.log("Square area:", square.area()); // 25

案例2：写十二个正方形程序（写十二遍程序）
这种方法非常低效，且难以维护。

案例3：使用for循环

function Square(side) {
  this.side = side;
}
Square.prototype.area = function() {
  return this.side * this.side;
};
for (let i = 1; i <= 12; i++) {
  const square = new Square(i);
  console.log(`Square ${i} area:`, square.area());
}

案例4：边长不全是5

function Square(side) {
  this.side = side;
}
Square.prototype.area = function() {
  return this.side * this.side;
};
const squares = [
  new Square(5),
  new Square(10),
  new Square(15)
];
for (const square of squares) {
  console.log(`Square area:`, square.area());
}

案例5：把对象放进原型里

function Shape() {}
Shape.prototype.area = function() {
  throw new Error("Not implemented");
};
function Square(side) {
  this.side = side;
}
Square.prototype = new Shape();
Square.prototype.area = function() {
  return this.side * this.side;
};
const square = new Square(5);
console.log("Square area:", square.area()); // 25

案例6：抽离到函数

function createSquare(side) {
  return {
    side: side,
    area: function() {
      return this.side * this.side;
    }
  };
}
const square = createSquare(5);
console.log("Square area:", square.area()); // 25

构造函数：可以构建对象

function Square(side) {
  this.side = side;
}
Square.prototype.area = function() {
  return this.side * this.side;
};
const square = new Square(5);
console.log("Square area:", square.area()); // 25