Javacript exmples initialize

Author: chethanagkiya

.vscode/launch.json

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+{
+ // Use IntelliSense to learn about possible attributes.
+ // Hover to view descriptions of existing attributes.
+ // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+ "version": "0.2.0",
+ "configurations": [
+ {
+ "name": "Current TS File",
+ "type": "node",
+ "request": "launch",
+ "args": ["${workspaceRoot}/test.ts"],
+ "runtimeArgs": ["--nolazy", "-r", "ts-node/register"],
+ "sourceMaps": true,
+ "cwd": "${workspaceRoot}",
+ "protocol": "inspector",
+ }
+ ]
+}

arrays.js

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+const list = require('./mock/list');
+
+function removeByFilter(array, index) {
+ console.log('indes', index);
+ return array.filter((el, ind) => ind !== index)
+}
+
+function removeBySplice(array, index) {
+ if (index !== -1) {
+ array.splice(index, 1); 
+ }
+ return array;
+ }
+
+/*******************
+ * Arrays
+ */
+let names = ['chethan', 'venkatesh', 'babu'];
+let num = new Array(1990, 1991, 1993);
+console.log(names);
+console.log(num.length);
+// console.log('removeByFilter', removeByFilter(list, 2));
+console.log('removeBySplice', removeBySplice(list, 1));
+
+

async-await.js

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+/*******************
+ * async / await
+ */
+const getIds = new Promise((resolve, reject) => {
+ setTimeout(() => {
+ resolve([123, 234, 345, 456]); // sucess then
+ }, 1500);
+});
+async function getCallAW() {
+ const IDS = await getIds;
+ console.log('11 ------------ ', IDS);
+}
+getCallAW();
+
+async function getNewCall() {
+ const IDS = await getIds;
+ return IDS;
+}
+getNewCall().then(ID => {
+ console.log(`20 --------------------- ${ID}`);
+});

async.js

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+/*********************************
+ * synchronous
+ */
+const second = () => {
+ console.log('Second');
+}
+
+const first = () => {
+ console.log('first');
+ second();
+ console.log('end');
+}
+first();
+/***********************************
+ * asynchronous
+ */
+console.log('------------------------------------------');
+const abc = () => {
+ setTimeout(() => {
+ console.log('Async call');
+ }, 2000);
+}
+
+const mnc = () => {
+ console.log('Starts');
+ abc();
+ console.log('ends');
+}
+mnc();
+//-------------------------------------------------------------
+function abc1() {
+ setTimeout(() => {
+ const q = [123, 234, 345, 456];
+ console.log('q', q);
+ setTimeout((id) => {
+ const res = {
+ publisher: 'asdfghjkl',
+ title: 'zxcvbnm'
+ };
+ console.log(`${id}--------${res.title}`);
+ }, 1000, q[2]);
+ }, 1500);
+}
+abc1();

bind.js

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+/**
+ * The bind() method creates a new function that, when called, has its this keyword set to the provided value,
+ * with a given sequence of arguments preceding any provided when the new function is called.
+ * -------------------------------------------------------------------------------------------
+ * bind() returns a bound function that, when executed later,
+ * will have the correct context ("this") for calling the original function.
+ * So bind() can be used when the function needs to be called later in certain events when it's useful.
+ */
+var module = {
+ x: 42,
+ getX: function() {
+ return this.x;
+ }
+ }
+ 
+ var unboundGetX = module.getX;
+ console.log("unboundGetX()", unboundGetX()); // The function gets invoked at the global scope
+ // expected output: undefined
+ 
+ var boundGetX = unboundGetX.bind(module);
+ console.log("boundGetX()", boundGetX());
+ // expected output: 42
+ // ------------------------------------------------------------------------------------
+ var obj = {name:"Niladri"};
+
+var greeting = function(a,b,c){
+ return "welcome "+this.name+" to "+a+" "+b+" in "+c;
+};
+
+console.log(greeting.call(obj,"Newtown","KOLKATA","WB"));
+// returns output as welcome Niladri to Newtown KOLKATA in WB

call.js

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+/**
+ * call()/apply() to invoke the function immediately.
+ * The call() method calls a function with a given this value and arguments provided individually.
+ */
+
+function Product(name, price) {
+ this.name = name;
+ this.price = price;
+ }
+ 
+ function Food(name, price) {
+ Product.call(this, name, price);
+ this.category = 'food';
+ }
+ 
+ console.log(new Food('cheese', 5).name);
+ // expected output: "cheese"

callbacks.js

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+// callback return values
+function foo(address, fn){
+ console.log('called');
+ fn(`${address} is my name`);
+ }
+ 
+ foo("chethan", function(value){
+ console.log(value); // this is where you get the return value
+ });
+
+ // initialContext calling
+loadInitScripts(() => {
+ console.log('script load');
+});
+
+// initialContext defining
+function loadInitScripts(callback) {
+ console.log('call back');
+ callback();
+}
+
+// another callback2 sum defining 
+function sum(callback, a, b) {
+ console.log('SUM', a + b);
+ callback(a + b);
+}
+// calling sum
+sum(function disp(value) {
+ console.log('anvavnabvan', value);
+}, 3, 4);

classExmp.js

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+class Human {
+ constructor() {
+ this.gender = 'FeMale';
+ }
+ printGender() {
+ console.log('gender', this.gender);
+ }
+}
+
+class Person extends Human {
+ constructor() {
+ super();
+ console.log('gender', this.gender)
+ this.name = 'Chethan';
+ this.gender = 'Male';
+ }
+
+ printName() {
+ console.log('name', this.name, this.printGender()); 
+ }
+}
+const person = new Person();
+person.printName();
+person.printGender();

closure.js

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+function makeAdder(x) {
+// parameter `x` is an inner variable
+// inner function `add()` uses `x`, so
+// it has a "closure" over it
+function add(y) {
+ console.log('y', y);
+return y + x;
+};
+return add;
+}
+
+// `plusOne` gets a reference to the inner `add(..)`
+// function with closure over the `x` parameter of
+// the outer `makeAdder(..)`
+var plusOne = makeAdder( 1 );
+
+// `plusTen` gets a reference to the inner `add(..)`
+// function with closure over the `x` parameter of
+// the outer `makeAdder(..)`
+var plusTen = makeAdder( 10 );
+console.log(plusOne( 3 ));// 4 <-- 1 + 3
+console.log(plusOne( 41 ));// 42 <-- 1 + 41
+console.log(plusTen( 13 ));// 23 <-- 10 + 13

common.js

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+class Common {
+ months() {
+ return ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
+ }
+}
+
+module.exports = new Common();