Javascript

Object Literal

//Example
var point = {x: 10, y: 20};

// With functions
var configuration = {
  allowResize: true,
  resize: function(width, height) {
    if (this.allowResize) {
      this.width = width;
      this.height = height;
    }
  }
};

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Function that returns an object

function createPoint(x, y) {
  return {x: x, y: y};
}

var createSegment = function(pointA, pointB) {
  function distance(axis) {
    return Math.abs(this.a[axis] - this.b[axis]);
  }

  return {
    a: pointA,
    b: pointB,
    getSize: function() {
      var x = distance.call(this, 'x');
      var y = distance.call(this, 'y');
      return Math.sqrt(x * x + y * y);
    }
  }
};
    

var pointA = createPoint(1, 1);
var pointB = createPoint(5, 3);

var segment = createSegment(pointA, pointB);
console.log(segment.getSize());

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Constructor Function

function Car(model, wheels, maxSpeed) {
  this.model = model;
  this.wheels = wheels;
  this.maxSpeed = maxSpeed;
  this.velocity = 0;

  this.accelerate = function() {
    this.velocity += 10;
  },

  this.brake = function() {
    this.velocity -= 10;
  }
}
var car = new Car('mini', 4, 240);
console.log(car);

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Constructor function + prototype

function Car(model, wheels, maxSpeed) {
  this.model = model;
  this.wheels = wheels;
  this.maxSpeed = maxSpeed;
  this.velocity = 0;
}

// Assigning properties to prototype object
Car.prototype.accelerate = function() {
  this.velocity += 10;
};
Car.prototype.brake = function() {
  this.velocity -= 10;
};

// Replacing prototype object with new one
Car.prototype = {
  accelerate: function() {
    this.velocity += 10;
  },
  brake: function() {
    this.velocity -= 10;
  }
};

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interlude: prototype chain

Object.create

// Crockford's shim
Object.create = function (o) {
    function F() {}
    F.prototype = o;
    return new F();
};
// Optimized version: Reuse function F
Object.create = (function () {
  function F() {} // created only once
  return function (o) {
    F.prototype = o; // reused on each invocation
    return new F();
  };
})();

var proto = {
  sayHello: function() {
    return "My name is " + this.name + " and I salute you!";
  }
};

var someone = Object.create(proto);

someone.name = "Lenny";

console.log(someone.sayHello());

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