Onur Dayıbaşı
Jul 1 · 2 min read

Question: What is the value of foo?

var foo = 10 + '20';console.log(foo);   //Result '1020' because its string concat operation

Question: What will be the output of the code below?

console.log(0.1 + 0.2 == 0.3);console.log(result);  //Result false because float keep binary in mem so when convert 0.1 or 0.2 to binary its not same 0.1 0.10000000001 etc.

Question: How would you make this work?

add(2, 5); // 7
add(2)(5); // 7
const add=(a, b)=>{
if(a && b) return a+b;
else return buffAdd=(b)=>{return a+b}
console.log(add(2, 5));

Question: What value is returned from the following statement?

"i'm a lasagna hog".split("").reverse().join("");const stringOpsResult="i'm a lasagna hog".split("").reverse().join("");
//goh angasal a m'i. how ? splits generates 17 char array all char reverse then the string generate

//if we split(" ") and join(" ") this time we generate 4 word array and we reverse word hog lasange a i'm

Question: What is the value of window.foo?

( window.foo || ( window.foo = "bar" ) );
console.log(window.go); //Result is 'bar' if we use && then second command not work so window.foo=undefined

Question: What is the outcome of the two alerts below?

var foo = "Hello"; (function() 
{var bar = " World"; alert(foo + bar);})(); //Alert=> Hello World
alert(foo + bar); // Reference Error bar is not defined

Question: What is the value of foo.length?

var foo = [];
console.log(foo.length); //Results is 2

Question: What is the value of foo.x?

var foo = {n: 1};
var bar = foo;
foo.x = foo = {n: 2}; //foo.x = (foo = {n:2}); => {n:1}.x = ( {n:1} = {n:2} ); R.H.S. foo={n:2}
console.log(foo.x); //Result undefined
console.log(foo); //Result {n:2}
console.log(bar); //Result {n:1, x: {n:2}}
Result = undefined

Question: What does the following code print?

setTimeout(function() {
}, 0);
Promise.resolve().then(function() {
//Result one, four , three, two its easy for one and four but theb why first three and then two prints.
//All of timeout and promise is async func..
//Answers is timeout in EventLoop Queue , promise process in JobQueue and JobQueue is high priority…

Question: What is the difference between these four promises?

//One level difficult..
//The answer https://gist.github.com/nolanlawson/940d1a390b2d9cf9483c

Promises answers

Frontend Development With JS

Frontend Development With Javascript

Onur Dayıbaşı

Written by

Senior Frontend Developer at Thundra

Frontend Development With JS

Frontend Development With Javascript

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