JavaScript Objects

const myCat = { \_name: 'Dottie', get name() { return this.\_name; }, set name(newName) { this.\_name = newName; } }; // Reference invokes the getter console.log(myCat.name); // Assignment invokes the setter myCat.name = 'Yankee'; 

const engine = { // method shorthand, with one argument start(adverb) { console.log(`The engine starts up ${adverb}...`); }, // anonymous arrow function expression with no arguments sputter: () => { console.log('The engine sputters...'); }, }; engine.start('noisily'); engine.sputter(); 

// A factory function that accepts 'name', // 'age', and 'breed' parameters to return // a customized dog object. const dogFactory = (name, age, breed) => { return { name: name, age: age, breed: breed, bark() { console.log('Woof!'); } }; }; 

const cat = { name: 'Pipey', age: 8, whatName() { return this.name } }; console.log(cat.whatName()); // => Pipey 

const activity = 'Surfing'; const beach = { activity }; console.log(beach); // { activity: 'Surfing' } 

const origNum = 8; const origObj = {color: 'blue'}; const changeItUp = (num, obj) => { num = 7; obj.color = 'red'; }; changeItUp(origNum, origObj); // Will output 8 since integers are passed by value. console.log(origNum); // Will output 'red' since objects are passed // by reference and are therefore mutable. console.log(origObj.color); 

const person = { firstName: "Matilda", age: 27, hobby: "knitting", goal: "learning JavaScript" }; delete person.hobby; // or delete person[hobby]; console.log(person); /\* { firstName: "Matilda" age: 27 goal: "learning JavaScript" } \*/ 

const person = { name: 'Tom', age: '22', }; const {name, age} = person; console.log(name); // 'Tom' console.log(age); // '22' 

const student = { name: 'Sheldon', score: 100, grade: 'A', } console.log(student) // { name: 'Sheldon', score: 100, grade: 'A' } delete student.score student.grade = 'F' console.log(student) // { name: 'Sheldon', grade: 'F' } student = {} // TypeError: Assignment to constant variable. 

const classElection = { date: 'January 12' }; console.log(classElection.place); // undefined 

// Example of invalid key names const trainSchedule = { // Invalid because of the space between words. platform num: 10, // Expressions cannot be keys. 40 - 10 + 2: 30, // A + sign is invalid unless it is enclosed in quotations. +compartment: 'C' } 

const apple = { color: 'Green', price: { bulk: '$3/kg', smallQty: '$4/kg' } }; console.log(apple.color); // => Green console.log(apple.price.bulk); // => $3/kg