Important things of JavaScript

important things of javascript

Primitive Values:

Primitive values in JavaScript are number, string, null, undefined, and booleans.

console.log(17);
console.log(‘Hello’);
console.log(undefined);
console.log(null);

Non-primitive Values:

Non-primitive Value in JavaScript is an object

const person = { name: ‘Fahim’, age: ‘20’ };

Objects

In JavaScript, a variable contains only one value. Objects are variable, but they can contain many values.

const person = { name: ‘Fahim’, age: 21, eyeColor: ‘Black’ };

Functions:

In JavaScript, the function is a set of statements and they can perform a particular task.

Syntax:

function function-name ( parameter1, parameter2, …….. , parameterN ) {
        // statements
}

Example:

function add( x, y ) {
return x + y;
}

Arrow functions

Arrow functions in ES6. It is a set of statements (with a parameter or without parameter ) and it can perform a particular task.

Syntax:

function-name = ( parameter ) => {
// statement
}

Example:

const add = ( x, y) => {
return x + y;
}

Hoisting:

In JavaScript, a variable declared for after use. Hoisting in JavaScript is a behavior in which a function or a variable can be used before declaration.

Example:

let x; // declared x
x = 10; // assign value of x

Error Handling

Error handling in JavaScript has to terms try and catch. The try statement lets you test for errors to block a code and catch statement handle error.

Syntax:

try{
//statement
}
catch(error){
//statement
}

Comments:

There are two types of comments in JavaScript. They are- single-line comments and multiline comments.

Single line comment:

Single line comment starts with //.

// single line comment
console.log(‘ok’);

Multi-line comment:

Multi-line comment starts with /* and ends with */.

/* multiline comment
Example comment
demo comment */
console.log(‘ok’);

Fahim Ahammed Firoz