/**
* @author: K. Lae Kettavong
* @date: 2/17/19
* @description: Using an IIFE to encapsulate an array implementation
*/
const ArrayImpl = (() => {
//private members
let _length = 0
let _data = {}
/*
* Removes element at specified index and move trailing elements to the left
*
* @param number index - element to remove
*/
const _shiftLeft = (index) => {
let counter = 0
Object.entries(_data).forEach(ele => {
if(ele[0] != index){
_data[counter] = ele[1]
counter++
}
})
delete _data[_length - 1]
_length--
}
/*
* Inserts element at beginning of array and move existing elements to the right
*
* @param string item - item to insert
*/
const _shiftRight = (item) => {
let data = {0: item}
let counter = 1
Object.entries(_data).forEach(ele => {
data[counter] = ele[1]
counter++
})
_length++
_data = data
}
// Anonymous class with public interface
return class {
/*
* Returns the element at the specified index
*
* @param number index - item index to fetch
* @return string - element at the given index
*/
get(index) {
return _data[index]
}
/*
* Adds item to the end of the array
*
* @param string item - item to add
* @return string item - item being inserted
*/
push(item) {
_data[_length] = item
_length++
return _length
}
/*
* Removes the last element in the array
*
* @return string item - item being removed
*/
pop() {
const item = _data[_length-1]
delete _data[_length-1]
_length--
return item
}
/*
* Adds item to the front of the array
*
* @param string item - item to add
* @return string item - item being inserted
*/
insert(item) {
_shiftRight(item)
return item
}
/*
* Removes the given element from arry and shifts remaining elements to the left
*
* @param number index - index of element to removed
* @return string item - item being removed
*/
delete(index) {
const item = _data[index]
_shiftLeft(index)
return item
}
/*
* Displays array content
*/
dump(){
console.log({ length: _length, data: _data })
}
}
})()
const array = new ArrayImpl()
array.push('One')
array.push('2')
array.push('Two')
array.push('Three')
array.push('!')
console.log(array._data) //undefined, cannot access private field
array.dump() // { length: 5, data: { '0': 'One', '1': '2', '2': 'Two', '3': 'Three', '4': '!' } }
console.log(array.delete(1)) // returns 2
array.dump() //{ length: 4, data: { '0': 'One', '1': 'Two', '2': 'Three', '3': '!' } }
console.log(array.pop()) // ! is returned
array.dump() // { length: 3, data: { '0': 'One', '1': 'Two', '2': 'Three' } }
array.insert('Start')
array.dump() //{ length: 4, data: { '0': 'Start', '1': 'One', '2': 'Two', '3': 'Three' } }
