Create javascript_array_methods.js

Author: kumarmeet

javascript_array_methods.js

@@ -0,0 +1,219 @@
+/*###########################################################################*/
+//Different ways to declaring an array
+const arr = [1, 2, 3];
+console.log(arr);
+
+const newArray = new Array(5); //fixed array size of 5
+console.log(newArray);
+
+const withourNewArray = Array(5); //fixed array size of 5
+console.log(withourNewArray);
+
+const ofArray = Array.of(1, 2);
+console.log(ofArray);
+
+const li = document.querySelectorAll("li"); //it will give array like object
+console.log(li);
+
+const fromArray = Array.from(li); //convert an array to array like object
+console.log(fromArray);
+//Different ways to declaring an array end
+/*###########################################################################*/
+
+/*###########################################################################*/
+//Data can store in an array
+const personalData = [
+	30,
+	"Meet",
+	{ moreDetail: ["M.P.", "Bhopal", "462002"] },
+	true,
+];
+console.log(personalData[2].moreDetail[1]);
+
+for (const i of personalData) {
+	console.log(i);
+}
+
+const matrix = [
+	[1, 5],
+	[14, 3],
+	[7, 9],
+];
+
+for (const i of matrix) {
+	for (const j of i) {
+		console.log(j);
+	}
+}
+//Different ways to declaring an array end
+/*###########################################################################*/
+
+/*###########################################################################*/
+//push, pop, shift and unshift
+const books = ["C in Depth", "C++"];
+console.log(books);
+books.push("Cracking the Coding Interview"); //add element at last and returns lenght
+console.log(books);
+books.unshift("Data Structures & Algorithms"); //add element at start and returns lenght
+console.log(books);
+books.unshift("Think Like a Monk");
+books.push("Marvels");
+console.log(books);
+
+//removes first element
+const firstRemovedElement = books.shift();
+console.log(`Removed first element -> ${firstRemovedElement}`);
+console.log(books);
+
+//removes last element
+const lastRemovedElement = books.pop();
+console.log(`Removed last element -> ${lastRemovedElement}`);
+console.log(books);
+//push, pop, shift and unshift end
+
+//splice method and it will return removed element(s)
+//first arg is index of array, 2nd arg is delete and 3rd arg add element on index
+books.splice(3, 0, "JavaScript", "Python", "Summer Vaccation");
+console.log(books);
+
+//first arg is index and second arg is for delete that index
+books.splice(5, 1);
+console.log(books);
+
+books.splice(
+	0,
+	0,
+	"Think Like a Monk",
+	"How to Influence People",
+	"Life Saver"
+);
+console.log(books);
+
+books.splice(0, 3); //It will delete from 0 to 2
+console.log(books);
+
+books.splice(3); //It will delete all elements from index 3
+console.log(books);
+
+books.splice(-2, 1); //It will start from end of the array and remove it
+console.log(books);
+
+books.splice(0); //It will delete all elements from an array
+console.log(books);
+//splice end
+/*###########################################################################*/
+
+/*###########################################################################*/
+//slice
+const testResult = [1, 4, 5, 3.3, -6, 47, "Calculus", -8, 13.44, "Algebra"];
+console.log(testResult);
+
+const storedResult = testResult.slice(); //copy an array not reference
+testResult.push(44);
+console.log(storedResult, testResult);
+
+//returns a brand new array, copy from begining
+const result = testResult.slice(0, 3);
+console.log(result);
+
+//returns a brand new array, copy from end
+const lastResult = testResult.slice(-4);
+console.log(lastResult);
+//slice end
+/*###########################################################################*/
+
+/*###########################################################################*/
+//concate
+//it will also return brand new copy and brand new address
+const arr1 = [1, 2, 3, 4, 5, 6];
+const arr2 = [7, 8, 9, 10, 11, 12];
+const concateArr = arr1.concat(arr2);
+console.log(concateArr);
+
+const concateAnotherArr = arr1.concat([
+	[11, 14, 15, 19, 20],
+	[31, 41, 22, 65],
+]);
+
+console.log(concateAnotherArr);
+
+const oneMoreConcateArr = arr2.concat([13, 14, 15, 16, 17]);
+console.log(oneMoreConcateArr);
+//concate end
+/*###########################################################################*/
+
+/*###########################################################################*/
+//indexOf and lastIndexOf
+const mobileModels = [
+	"Redmi Note 7",
+	"One Plus+",
+	"Samsung M3",
+	"One Plus+",
+	"Nokia 5530",
+];
+console.log(mobileModels);
+//indexOf returns first occurence index of found element, even that element exist more than one times
+//indexOf searching starts from left
+let found = mobileModels.indexOf("One Plus+", 0);
+
+if (found >= 0) {
+	console.log(`Found Item on index ${found}`);
+}
+
+//indexOf returns last occurence index of found element, even that element exist more than one times
+//lastIndexOf searching starts from right
+found = mobileModels.lastIndexOf("One Plus+", -1);
+
+if (found >= 0) {
+	console.log(`Found Item on index ${found}`);
+}
+
+const person = [{ language: "English" }, { language: "Hindi" }];
+//the below line won't work coz object has address and we check different address in indexOf
+found = person.indexOf({ language: "English" }); //it will give -1
+
+if (found < 0) {
+	console.log(`Not found Item`);
+}
+//indexOf and lastIndexOf end
+/*###########################################################################*/
+
+/*###########################################################################*/
+//find and findIndex
+const districtName = [
+	{ city: "Bhopal" },
+	{ city: "Indore" },
+	{ city: "Banglore" },
+];
+
+//find doesn't create a copy
+//find return matching item
+let city = districtName.find((district, idx, cities) => {
+	return district.city === "Bhopal";
+});
+
+console.log(city);
+
+//findIndex return index of the item
+city = districtName.findIndex((district, idx, cities) => {
+	return district.city === "Banglore";
+});
+
+console.log(city);
+//find and findIndex end
+/*###########################################################################*/
+
+/*###########################################################################*/
+//includes
+const percentage = [44, 85, 99, 34, 65, 71];
+
+//includes return true if element has in an array other wise false
+if (percentage.includes(99, 0)) {
+	console.log("Found");
+}
+
+if (!percentage.includes(15)) {
+	console.log("Not Found");
+}
+//includes end
+/*###########################################################################*/