(Javascript) My learning journey Part 5: Array, Object and loop

// Data store one by one name1 = 'Mike' name2 = 'Paul' name3 = 'John' // More efficiently store in a array names = ['Mike', 'Paul', 'John'] // Alternative declaration names = new Array('Mike', 'Paul', 'John') // Accessing a specific array element console.log(names[0]) // Mike console.log(names[1]) // Paul console.log(names[2]) // John // Number of entry in array console.log(names.length)) // 3 // Get array last element console.log(names[names.length-1]) // Modify a specific element names[0] = 'Jack' // replace first entry (Mike) with Jack // 

names = ['Mike', 'Paul', 'John'] // Add a element to array names.push('Simon') // ['Mike', 'Paul', 'John', 'Simon'] // Add a element to the beginning  names.unshift('Jack') // ['Jack', 'Mike', 'Paul', 'John', 'Simon'] // Remove last element names.pop() // ['Jack', 'Mike', 'Paul', 'John'] // Remove first element names.shift() // ['Mike', 'Paul', 'John'] names = ['Mike', 'Paul', 'John'] // Find element index position names.indexOf('Paul') // 1 // If elements includes in array names.includes('Paul') // true 

// Object declaration const customer = { firstName: 'Mike', // String lastName: 'Tailor', // String emails: ['mike@exemple.com', 'mike2@gmail.com'], //Array creditLimit: 2500 // Number } // Access object property console.log(customer.firstName) // Mike // or console.log(customer['firstName']) // Mike // Add property customer.phone = "800-828-1240" // or customer['phone'] = "800-828-1240" 

const phone = { number: '819-204-5678', extension: '2010', } const customer = { firstName: 'Mike', lastName: 'Tailor', phone: phone, // or short hand (if property same name as value) phone, fullName: function() { // this keyword reference the object calling the method return this.firstName + ' ' + this.lastName } // or the short hand syntax fullName() { // this keyword reference the object calling the method return this.firstName + ' ' + this.lastName } } customer.firstName = 'Mike' customer.lastName = 'Taylor' console.log(customer.fullName()) // Mike Taylor // or  console.log(customer['fullName']() // Mike Taylor // object keys const keys = Object.keys(customer) console.log(keys) // firstName, lastName, phone, fullName // object values const values = Object.values(customer) console.log(keys) // 'Mike', 'Taylor', {number: '819-243-4554', extension: '20'}, function fullName() 

// For Loop keep running until condition is true for (let i = 1;i <= 10; i++) { console.log(i) } // For Loop : Break and Continue keyword for (let i = 1;i <= 10; i++) { if (i === 1) continue // go directly to next interation if (i === 5) break // stop and exit loop console.log(i) } // Loop within a Array names = ['Mike', 'Paul', 'John'] for (let i = 0;names.length - 1; i++) { console.log(names[i]) } // While loop let count = 1 while (count <= 10) { count++ console.log(count) } // For of loop names = ['Mike', 'Paul', 'John'] for (const name of names) { console.log(name) } // For of loop with index (destructuring) for (const [name, index] of names.entries()) { console.log(name) // 'Mike' console.log(index) // 0 } // Object: keys and values (destructuring) for (const [key, value] of Object.entries(customer)) { console.log(key) // firstName console.log(value) // Mike }