JS Syntax
The set of guidelines used to design JavaScript programs is known as JavaScript syntax:
// How to create variables:
var x;
let y;
// How to use variables:
x = 5;
y = 6;
let z = x + y;
JavaScript Values
Two categories of values are defined by the JavaScript syntax:
- Set values
- Variable amounts
Literals are defined as fixed values.
We refer to variable values as variables.
JavaScript Literals
For fixed values, the following two syntactic rules are extremely important:
- Decimals can be used or not when writing numbers:
10.50
1001
- 2. Text placed in single or double estimates is called a string.
"John Doe"
'John Doe'
JavaScript Variables
Variables are used in programming languages to store values of data.
To declare variables in JavaScript, use the keywords var, let, and const.
Values are assigned to variables using the equal sign.
x is defined as a variable in this example. Next, the number 6 is assigned (given) to x:
let x;
x = 6;
JavaScript Operators
JavaScript computes values using the arithmetic operators (+ – * /):
(5 + 6) * 10
JavaScript assigns values to variables using the assignment operator (=):
let x, y;
x = 5;
y = 6;
JavaScript Expressions
A set of values, variables, and operators that add up to a value is called an expression.
We refer to the calculation as an evaluation.
For instance, 5 * 10 equals 50.
5 * 10
Variable values can also be found in statements:
x * 10
Different types of values, including strings and numbers, are possible.
For instance, “John” plus “” plus “Doe” equals “John Doe”:
x * 10
JavaScript Keywords
Actions that need to be completed are identified by JavaScript keywords.
The browser is shown how to create variables using the let keyword:
let x, y;
x = 5 + 6;
y = x * 10;
The browser is also directed to create variables by the var keyword
var x, y;
x = 5 + 6;
y = x * 10;
Using let or var in these cases will get the same outcome.
var and let are two more topics you will cover in this tutorial.
JavaScript Comments
Not every statement in JavaScript is “executed”.
Comment is applied to code that comes after double slashes // or in between /* and */.
Remarks are not taken seriously and won’t be implemented:
Example
let x = 5; // I will be executed
// x = 6; I will NOT be executed
A later chapter will cover comments in more detail.
JavaScript Identifiers / Names
JavaScript names are used as identifiers.
Functions, variables, and keywords are all named using identifiers.
In most computer languages, the rules related to legal names are the same.
JavaScript names have to start with:
- A letter (A-Z or a-z)
- A dollar sign ($)
- Or an underscore (_)
The characters that follow can be dollar signs, underscores, letters, or numerals.
Note :
In names, numbers cannot appear as the initial character.
In this manner, JavaScript quickly differentiates between identifiers and integers.
JavaScript is Case Sensitive
All identifiers in JavaScript are case-sensitive.
There are two separate variables, lastName and lastname:
let lastname, lastName;
lastName = "Doe";
lastname = "Peterson";
LET or Let is not translated by JavaScript as the keyword let.
JavaScript and Camel Case
Programmers have combined several words into a single variable name in the past using a variety of techniques:
hyphens:
First name, last name, master card, inter-city.
In JavaScript, hyphens are not permitted. They’re kept aside for subtraction.
Underscore:
first_name, last_name, inter_city, master card.
Camel Case Upper (Pascal Case)
FirstName, LastName, InterCity, MasterCard.
Lower Camel Case:
JavaScript programmers typically begin their sentences with a lowercase letter (called camel case):
Master Card, InterCity, firstName, lastName.
JavaScript Character Set
Unicode character sets are used by JavaScript.
Almost every character, punctuation mark, and symbol in the world is covered by Unicode.
