What is == and === in JavaScript?

The main difference between the == and === operator in javascript is that the == operator does the type conversion of the operands before comparison, whereas the === operator compares the values as well as the data types of the operands.

What does === mean in JavaScript?

The === operator means "is exactly equal to," matching by both value and data type. The == operator means "is equal to," matching by value only.

What's the difference between == and === operators?

The difference between == and === is that: == converts the variable values to the same type before performing comparison. This is called type coercion. === does not do any type conversion (coercion) and returns true only if both values and types are identical for the two variables being compared.

What is the difference between == and === operator in JavaScript illustrate with examples?

In one word, main difference between "==" and "===" operator is that formerly compares variable by making type correction e.g. if you compare a number with a string with numeric literal, == allows that, but === doesn't allow that, because it not only checks the value but also type of two variable, if two variables are ...

What is double equal and triple equal in JavaScript?

Double Equals ( == ) checks for value equality only. It inherently does type coercion. This means that before checking the values, it converts the types of the variables to match each other. On the other hand, Triple Equals ( === ) does not perform type coercion.

== vs === - Beau teaches JavaScript

Which is faster == or === in JavaScript?

So === faster than == in Javascript

=== compares if the values and the types are the same. == compares if the values are the same, but it also does type conversions in the comparison. Those type conversions make == slower than ===.

What is the difference between == and === in JavaScript Mcq?

== is used for the comparison between two variables regardless of the type of the variable. === is used for a strict comparison between two variables i.e. it will check the type and value of both variables, which means it will check the type and compare the two values.

What are the 4 types of JavaScript operators?

What is the difference between null & undefined?

In JavaScript, undefined is a type, whereas null an object. It means a variable declared, but no value has been assigned a value. Whereas, null in JavaScript is an assignment value. You can assign it to a variable.

What is callback function in JavaScript?

A JavaScript callback is a function which is to be executed after another function has finished execution. A more formal definition would be - Any function that is passed as an argument to another function so that it can be executed in that other function is called as a callback function.

What does ++ mean in JavaScript?

The increment operator ( ++ ) increments (adds one to) its operand and returns a value.

What is difference between VAR and let in JavaScript?

let is block-scoped. var is function scoped. let does not allow to redeclare variables. var allows to redeclare variables.

What is the difference between >> and >>> operators in JavaScript explain?

>> is arithmetic shift right, >>> is logical shift right. In an arithmetic shift, the sign bit is extended to preserve the signedness of the number.

What === means?

The triple equals sign === checks to see whether two variables are equal and of the same type.

What is promise in JavaScript?

The Promise object represents the eventual completion (or failure) of an asynchronous operation and its resulting value. Note: This feature is available in Web Workers. To learn about the way promises work and how you can use them, we advise you to read Using promises first.

What is NaN in JavaScript?

In JavaScript, NaN is short for "Not-a-Number". In JavaScript, NaN is a number that is not a legal number.

What are data types in JS?

In Javascript, there are five basic, or primitive, types of data. The five most basic types of data are strings, numbers, booleans, undefined, and null.

Why typeof null is object?

In JavaScript, typeof null is 'object', which incorrectly suggests that null is an object. This is a bug and one that unfortunately can't be fixed, because it would break existing code.

What is a closure in JavaScript?

A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In other words, a closure gives you access to an outer function's scope from an inner function.

What is array in JavaScript?

Arrays are a special type of objects. The typeof operator in JavaScript returns "object" for arrays. But, JavaScript arrays are best described as arrays. Arrays use numbers to access its "elements".

What does 3 dots mean in JavaScript?

(three dots in JavaScript) is called the Spread Syntax or Spread Operator. This allows an iterable such as an array expression or string to be expanded or an object expression to be expanded wherever placed.

What is string in JavaScript?

A string is a sequence of one or more characters that may consist of letters, numbers, or symbols. Strings in JavaScript are primitive data types and immutable, which means they are unchanging.

What is the difference between undeclared & undefined?

The difference between undefined and undeclared variables in JavaScript is: Undefined variable means a variable has been declared but it does not have a value. Undeclared variable means that the variable does not exist in the program at all.

What is a block statement in JavaScript?

The block statement is often called compound statement in other languages. It allows you to use multiple statements where JavaScript expects only one statement. Combining statements into blocks is a common practice in JavaScript.

How do you clear an array in JavaScript?