Learning JavaScript tutorial – Lexical Structure and Statements

Learning JavaScript tutorial – Lexical Structure and Statements

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A JavaScript statement is a command to a web browser to perform specific task define (program written) by the user. JavaScript Statements are written with the set of elementary rules that specifies how to write JavaScript programs. A JavaScript program is a set of one or more statements. A statement will have internal components like Variables, Literals, Identifier, reserved keywords, Comments, conditional statement, Arrays, Functions, Objects, Classes etc

JavaScript is case sensitive, in the most of cases JavaScript Statements terminated with a semicolon(;) or with Returns(Enter or line-break). Even though semicolon is optional, JavaScript Statements terminated with a semicolon(;) is the best practice of JavaScript programming.

var txtName="I love JavaScript";
var intNum=10

semicolons allows us to group multiple statements on one line.

x = x + 1;  y = 20;  z = x+y;

As the semicolon is optional, we can represent above statements separated with a line-break.

x = x + 1
y = 20
z = x+y

Categories of JavaScript Statements

Depending on the task a statement perform, they are categories as:

  • Conditional Statements
  • Loop Statements
  • Object Manipulation Statements
  • Comment Statements
  • Exception Handling Statements

JavaScript Blocks – Group of JavaScript Statements

JavaScript statements can be grouped together in blocks. Curly braces ({ }) are used to group a list of statements together in blocks. JavaScript block helps to execute sequence of statements together to perform a specific task. JavaScript block are the integral part of the function and conditional loops.

<script type="text/javascript">
for (x=0; x < 10; x++)
  document.write("x="+ x +"<br>");

Some Tips on declaring a JavaScript Statement

  • JavaScript programs are written using the Unicode character set.
  • JavaScript is a case-sensitive language so take care while defining and using variables, function names.
  • Do not use reserved keywords as variables, function names.
  • JavaScript ignores spaces, tabs, and newlines that appear between tokens in programs so indent your programs as per your consistency.
  • Omitting semicolons is not a good programming practice; you should get in the habit of using them.


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