Null Vs Undefined
JavaScript undefined mean variable is clear but has not yet been signed in value
Double Equal Vs Triple Equal
Double == equal sign test for abstract equality
Triple === equal sign test for strict equality.
console.log(3 == “3”); True
console.log(3 === “3”); False
Closure
A closure is the combination of a function and the environment with in which that function was declared. JavaScript all function from closure
function myFunc(){
var name = “JS Func”;
function displayName() {
console.log(name);
}
return displayName;
}
var makeFunc = myFunc();
makeFunc(); // JS Func
Difference between bind, call and apply
Bind return a new function. permission to pass any number of arguments.
call method invokes a function given this value and argument.
Apply invokes the function with given this value allows you pass in argument as in an array.
What is Scope?
Scope ultimate the visibility or accessibility of a variable or other basics in the area of your code.
Two kinds of scope is: global scope and local scope.
What is Block scope?
Block scope is the area if, switch condition or for and while loops. Commonly speaking when you see curly braces {} it is a block in ES6. const and let keyword allow developers to confirm variables in the block scope.
What is Asynchronous?
Asynchronous programming means in an event loop. When blocking operation is essential. The request is started and the code keeps running without blocking for result.
JavaScript key features
Javascript is one of the most popular languages. Javascript key features is
1: Lightweight scripting languages
2: Dynamic typing
3:Functional style
4: prototype-based language.
What is an event bubble?
An event bubble is a type of event generation where the event is first caught by the outermost element.
What is this keyword?
this keyword refers to the object that the function is a property of. The value of this keyword will always trust in the object that is the function.
