Part 02 of Basics / 01 Arrays in JS

Learned about Declaring, accessing, using different methods, converting to strings all in Arrays. Also learned some complex ones like splice and slice.

Author: aayushyadavz

02_Basics/01_arrays.js

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+/* 1. Arrays
+
+(i) Declaring Array, */
+const myArr = [0, 1, 2, 3, 4]
+// console.log(myArr[2]); // Output: 2 | Accsessing value of an Array.
+// Note: Array indexing starts from Zero.
+const heros = ["Thor", "IronMan", "SpiderMan"]
+// console.log(heros); // Output: [ 'Thor', 'IronMan', 'SpiderMan' ]
+const myArr2 = new Array(1, 2, 3, 4)
+// console.log(myArr2); // Output: [ 1, 2, 3, 4 ]
+/* Note: Run const numbers = [1, 2, 3, 4] in browser's console to see prototype access in Arrays.
+
+-----------------------------------------------------------------------------------------------------
+
+(ii) Array Methods, */
+myArr.push(6)
+// console.log(myArr); // Output: [ 0, 1, 2, 3, 4, 6 ] | Pushes element in the end of the array.
+myArr.pop()
+// console.log(myArr); // Output: [ 0, 1, 2, 3, 4 ] | Removes element from the end of the array.
+myArr.unshift(9)
+// console.log(myArr); // Output: [ 9, 0, 1, 2, 3, 4 ] | Adds element to the starting of the array.
+myArr.shift()
+// console.log(myArr); // Output: [ 0, 1, 2, 3, 4 ] | Removes element from the starting of the array.
+
+// console.log(myArr.includes(9)); // Output: false
+
+// console.log(myArr.indexOf(4)); // Output: 4 
+// Note: Indexing starts from Zero.
+// console.log(myArr.indexOf(9)); // Output: -1
+// Asking any value which doesn't exist in index gives you -1.
+
+const newArr = myArr.join()
+// console.log(newArr); // Output: 0,1,2,3,4
+// console.log(typeof newArr); // Output: string
+/* Note: .join binds and converts array into strings.
+
+-----------------------------------------------------------------------------------------------------
+
+(iii) slice, splice (Methods) */
+console.log("A ", myArr); // Output: A  [ 0, 1, 2, 3, 4 ]
+const myNewArr1 = myArr.slice(1, 3) /* Include value at index 1 and 2 but don't 
+include value at index 3. */
+console.log(myNewArr1); // Output: [ 1, 2 ]
+console.log("B ", myArr); // Output: B  [ 0, 1, 2, 3, 4 ]
+// Note: As we can see using slice doesn't affect original array.
+
+const myNewArr2 = myArr.splice(1, 3)
+console.log(myNewArr2); // Output: [ 1, 2, 3 ]
+console.log("C ", myArr); // Output: C  [ 0, 4 ]
+// Note: But in splice we can see it removes the elements and manipulates the original array.
+