tech(array): array operations

Author: shangan23

array/common-operations.js

@@ -0,0 +1,81 @@
+// Create an Array
+let fruits = ['Apple', 'Banana']
+
+/**
+ * Common Operations
+ * length
+ * access
+ * iterate/loop
+ * push
+ * pop
+ * indexOf
+ * shift
+ * unshift
+ * splice
+ * slice
+ */
+
+// length
+console.log(fruits.length) // 2
+
+// Access an Array item using the index position
+console.log(fruits[0]) // Apple
+
+// Loop over an Array
+fruits.forEach(function (item, index, array) {
+  console.log(item, index)
+})
+// Apple 0
+// Banana 1
+
+// Add an item to the end of an Array
+let newLength = fruits.push('Orange')
+// ["Apple", "Banana", "Orange"]
+
+// Remove an item from the end of an Array
+let last = fruits.pop() // remove Orange (from the end)
+// ["Apple", "Banana"]
+
+// Remove an item from the beginning of an Array (reverse of pop)
+let first = fruits.shift() // remove Apple from the front
+// ["Banana"]
+
+// Add an item to the beginning of an Array (reverse of push)
+fruits.unshift('Strawberry') // add to the front
+// ["Strawberry", "Banana"]
+
+// Find the index of an item in the Array
+fruits.push('Mango')
+// ["Strawberry", "Banana", "Mango"]
+
+let pos = fruits.indexOf('Banana') // case sensitive; returns -1 if not found
+// 1
+
+// Remove an item by index position
+let removedItem = fruits.splice(pos, 1) // this is how to remove an item
+// ["Strawberry", "Mango"]
+
+// Remove items from an index position
+let vegetables = ['Cabbage', 'Turnip', 'Radish', 'Carrot']
+console.log(vegetables)
+// ["Cabbage", "Turnip", "Radish", "Carrot"]
+
+let pos = 1
+let n = 2
+
+let removedItems = vegetables.splice(pos, n)
+// this is how to remove items, n defines the number of items to be removed,
+// starting at the index position specified by pos and progressing toward the end of array.
+
+console.log(vegetables)
+// ["Cabbage", "Carrot"] (the original array is changed)
+
+console.log(removedItems)
+// ["Turnip", "Radish"]
+
+// Copy an Array
+let shallowCopy = fruits.slice() // this is how to make a copy
+// ["Strawberry", "Mango"]
+
+console.log(fruits)
+//["Strawberry", "Mango"] (the original array remain same)