const words = ['will', 'rock', 'you!']
// output ['will', 'rock', 'you!']
console.log(words)
// returns 4
words.unshift('We')
// output ['We', 'will', 'rock', 'you!']
console.log(words)December 5th, 2019
unshift() adds items to the beginning of an array and returns the length of the new array.
const words = ['Hello', 'Mischa', 42]
// output: ['Hello', 'Mischa', 42]
console.log(words)
// returns 42
words.pop()
// output: ['Hello', 'Mischa']
console.log(words)December 4th, 2019
pop() removes the last item from the original array and returns it.
const words = ['Ohayou', 'Gozaimasu']
// output ['Ohayou', 'Gozaimasu']
console.log(words)
// returns 'Ohayou'
words.shift()
// output ['Gozaimasu']
console.log(words)December 4th, 2019
shift() removes an item from the beginning of an array and returns the remove item.
const words = ['No', 'one', 'lives']
// output: ['No', 'one', 'lives']
console.log(words)
// returns 4 <- length of the new array
words.push('Forever!')
// output: ['No', 'one', 'lives', 'Forever!']
console.log(words)December 4th, 2019
push() adds items to the end of an array and returns the length of the new array.
const obj1 = {a: 1, b: 2}
const obj2 = {c: 3, a: 4}
// option #1: Object.assign
const obj3 = Object.assign(obj1, obj2)
// option #2: spread operator
const obj4 = {...obj1, ...obj2}
// output: { a: 4, b: 2, c: 3 }
console.log(obj3)
// output: { a: 4, b: 2, c: 3 }
console.log(obj4)December 1st, 2019
Both the Spread Operator (...) and Object.assign(target, ...sources) can be used to copy an object by it's values and creates a new object without reference to the source object.