Update 100_JS_Que

Author: priya42bagde

100Questions/100_JS_Que

@@ -365,6 +365,181 @@ function getAge(){
 getAge();
 //Explaination : Use strict wil give a error because it forces to use a proper way of the variable declaration.
 ----------------------------------------------------------------------
+const sum = eval('10*10+5');
+console.log(sum); //105
+//Explaination : It will perform the numerical operation
+----------------------------------------------------------------------------
+const obj = {1:"a", 2:"b"}
+console.log(obj.hasOwnProperty("1")); //true
+console.log(obj.hasOwnProperty(1)); //true
+//Explaination : "1" and 1 treat as same.
+----------------------------------------------------------------------------
+const obj = {a:"one", b: "two", a:"three"}
+console.log(obj); // {a:"three", b: "two"}
+//Explaination : Key position will be same but tha value get updated with new value in object.
+----------------------------------------------------------------------------
+for(let i=1; i<5; i++){
+  if(i==3) continue;
+  console.log(i); //1,2,4
+}
+//Explaination : If i =3 then it will not execute the code for 3, but can execute for i=4.
+------------------------------------------------------------------------------
+const foo = () => console.log("first");
+const bar = () => setTimeout(()=> console.log("second"));
+const baz = () => console.log("third");
+bar();
+foo();
+baz();
+//Explaination : first,third, second. Because asyn operation work post all the syn operation get complete.
+----------------------------------------------------------------------------
+<div onClick="console.log("first div")">
+  <div onClick="console.log("second div")">
+    <button onClick="console.log("button")">
+     Click Me
+     </button>
+  </div>
+</div>
+//Explaination : button, second div, first div. Even bubbling happened here.
+---------------------------------------------------------------------------
+const person = {name:'priya'};
+function sayHi(age){
+  return `${this.name} is ${age}`;
+}
+console.log(sayHi.call(person,21)); //"priya is 21"
+console.log(sayHi.bind(person,21)); //it will return a function. //function sayHi(age){  return `${this.name} is ${age}`;}
+console.log(sayHi.bind(person,21)()); //"priya is 21"
+//Explaination : Bind will always return a function so require to invoke the function.
+------------------------------------------------------------------------------
+function sayHi(){
+  return (()=>0)();
+}
+console.log(typeof sayHi()); //number
+//Explaination : sayHi will return anonymous arrow function/IIFE, where it will return 0. type of 0 is number.
+----------------------------------------------------------------------------
+function sayHi(){
+  return ()=>0;
+}
+console.log(typeof sayHi()); //function
+console.log(typeof sayHi()()); //function
+//Explaination : sayHi will return anonymous arrow function/IIFE, where we didn't invole the arroe function so it will return function.
+-----------------------------------------------------------------------------
+console.log(typeof typeof 1); //string
+//Explaination : typeof 1 is a number and typeof number is a string.
+-----------------------------------------------------------------------------
+const numbers = [1,2,3];
+numbers[6]=11;
+console.log(numbers); //[1,2,3,,,,11]
+//Explaination : Array store elements in a continuous memory location. It will give empty in between an array.
+-------------------------------------------------------------------------------
+const numbers = [1,2,3];
+numbers[9]=numbers;
+console.log(numbers); //[1,2,3,,,,.......]
+//Explaination: It will print infinite loop.
+-------------------------------------------------------------------------------
+console.log(!!null); //false
+console.log(!!""); //false
+console.log(!!1); //true
+//Explaination: !null give true and !!null give false. !1 give false and then !!1 give true.
+-------------------------------------------------------------------------------
+console.log(setInterval(()=>console.log('Hi'), 1000));
+console.log(setInterval(()=>console.log('Hi'), 1000));
+console.log(setInterval(()=>console.log('Hi'), 1000));
+//Explaination: setInterval will give uniques id to stop. It will give like 1,2,3. so it will print 1,2,3,Hi,Hi, Hi, Hi, Hi, .....so on.
+-------------------------------------------------------------------------------
+console.log([..."priya"]); //["p","r","i","y","a"]
+//Explaination: It will convert into an array.
+-------------------------------------------------------------------------------
+const firstPromise = new Promise((res, rej)=>{
+  setTimeout(res, 500, 'one');
+})
+const secondPromise = new Promise((res, rej)=>{
+  setTimeout(res, 100, 'second');
+})
+Promise.race([firstPromise, secondPromise]).then(res => console.log(res));
+//Explaination: Race will return only first matching result so it will print 100. For 500 it will take time to execute so it will not get print.
+-----------------------------------------------------------------------------------
+let person = {name: "priya"};
+const numbers = [person];
+person = null;
+console.log(numbers, person); // [{name : "priya"}] //null
+//Explaination: We try to empty the objecti,e person, but still an array i.e, numbers conatin value so it will not create an impact while assigning null to person.
+----------------------------------------------------------------------------------
+const person = {name: "priya", age: 1000};
+for(const item in person){
+  console.log(item); //name, age
+}
+//Explaination: For in loop give a keys only.
+--------------------------------------------------------------------------------------
+let data = 3+4+'5';
+console.log(data); //"75"
+console.log(typeof data); //string
+//Explaination: It will add as a string.
+------------------------------------------------------------------------------------------
+console.log(typeof 3+4+'5'); //"number45"
+//Explaination: operation went from left to right side.
+----------------------------------------------------------------------------------------
+console.log(typeof (3+4+'5')); //"75" //string
+console.log(typeof (3+4+  +'5'));//number
+//Explaination: To find out the typeof when the all the operation get complete thrn have to enclose in paranethisis. If we add + plus sign to any string it will convert to a number.
+----------------------------------------------------------------------------------------
+que 91
+----------------------------------------------------------------------------------------
+----------------------------------------------------------------------------------------
+----------------------------------------------------------------------------------------
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