Array().join(" ") & Object & Property & 객체의 property로 담겨있는 function이 method처럼 작동 & 'in' & 객체에 property를 더하고 빼는법 & class.prototype.method()

describe("Object에 관해서", function() {

describe("Property에 관해서", function() {

let meglomaniac;

 

beforeEach(function() {

meglomaniac = { mastermind: "Joker", henchwoman: "Harley" };

});

 

it("객체에 property가 존재하는지 확인합니다.", function() {

expect(meglomaniac.mastermind).toBe("Joker");

});

 

it("객체의 property는 알파벳 대소문자를 구분합니다.", function() {

expect(meglomaniac.henchwoman).toBe("Harley");

expect(meglomaniac.henchWoman).toBe(undefined);

});

});

 

it("객체의 property로 담겨있는 function이 method처럼 작동하는지 확인합니다.", function() {

const meglomaniac = {

mastermind: "Brain",

henchman: "Pinky",

battleCry: function(noOfBrains) {

return (

"They are " +

this.henchman +

" and the" +

Array(noOfBrains + 1).join(" " + this.mastermind) // " " 만큼 간격을 주고 합친다.

);

}

};

 

const battleCry = meglomaniac.battleCry(4);

expect("They are Pinky and the Brain Brain Brain Brain").toMatch(battleCry);

});

 

it("'this'에 관해서", function() {

const currentDate = new Date();

const currentYear = currentDate.getFullYear();

const meglomaniac = {

mastermind: "James Wood",

henchman: "Adam West",

birthYear: 1970,

calculateAge: function() {

return currentYear - this.birthYear;

}

};

 

expect(currentYear).toBe(2020);

expect(meglomaniac.calculateAge()).toBe(50);

});

 

describe("'in'에 관해서", function() {

let meglomaniac;

beforeEach(function() {

meglomaniac = {

mastermind: "The Monarch",

henchwoman: "Dr Girlfriend",

theBomb: true

};

});

 

it("'theBomb'이라는 key를 가지고 있어야 합니다.", function() {

const hasBomb = "theBomb" in meglomaniac;

 

expect(hasBomb).toBe(true);

});

 

it("'theDetonator'라는 key를 가지고 있어선 안됩니다.", function() {

const hasDetonator = "theDetonator" in meglomaniac;

 

expect(hasDetonator).toBe(false);

});

});

 

it("객체에 property를 더하고 빼는법을 확인합니다.", function() {

const meglomaniac = { mastermind: "Agent Smith", henchman: "Agent Smith" };

 

expect("secretary" in meglomaniac).toBe(false);

 

meglomaniac.secretary = "Agent Smith";

expect("secretary" in meglomaniac).toBe(true);

 

delete meglomaniac.henchman;

expect("henchman" in meglomaniac).toBe(false);

});

 

it("prototype를 사용해 모든 instance 객체에 property와 method 추가하는 법을 확인합니다.", function() {

function Circle(radius) {

this.radius = radius;

}

 

let simpleCircle = new Circle(10); // 10

let colouredCircle = new Circle(5); // 5

colouredCircle.colour = "red";

 

expect(simpleCircle.colour).toBe(undefined); // 10

expect(colouredCircle.colour).toBe("red"); // 5

 

Circle.prototype.describe = function() {

return "This circle has a radius of: " + this.radius;

};

 

expect(simpleCircle.describe()).toBe("This circle has a radius of: 10");

expect(colouredCircle.describe()).toBe("This circle has a radius of: 5");

});

});