We have seen some great topics like map
, filter
, reduce
and much more in the previous blogs, So here is a simple concept in JavaScript ๐
Expression
Expression is a piece of code that produces a value.
Here is a small example,
// These are expression and it is gonna produce a value
3 + 4
6 - 3
4 / 2
true && false && !true
JavaScript has the following expression categories
String Expressions:
String expressions are expressions that evaluate a string.
'hello';
Logical Expression
Expressions that evaluate the boolean value true or false are considered to be logical expressions.
10>4
10<5
Left-hand-side Expressions: Left-hand-side expressions are those that can appear on the left side of an assignment expression.
// variables such as a
a =10;
// elements of arrays
b[3] = 3;
Assignment Expressions: When expressions use the = operator to assign a value to a variable, it is called an assignment expression.
b = 32;
age = 43;
str = `You are dumb ๐`
Statements
It is a bigger piece of code that is executed but doesn't produce a value
if(5>4) {
const str = `5 is bigger`
}
In the above code, it doesn't produce any value it simply declares the str
variable. This is completely different from having 3 + 4
.
Declaration Statements:
Such type of statements create variables and functions by using the var and function statements respectively.
function greet(message) => {console.log(message);}
Expression Statements:
Wherever JavaScript expects a statement, you can also write an expression. Such statements are referred to as expression statements. But the reverse does not hold. You cannot use a statement in the place of an expression.
// results in error as you can pass only expressions as a function argument
console.log(var a);
Conditional Statements:
Conditional statements execute statements based on the value of an expression. Examples of conditional statements include the if..else and switch statements.
// Ignore the format ๐
if (expression) {
statement 1 }
else {
statement 2 }
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