JavaScript Expressions and Statements

In JavaScript expressions and statements are two fundamental building blocks used to construct programs. They serve different purposes and have different characteristics.

Expressions

• An expression is any valid unit of code that evaluates to a value
• It can be as simple as a single value or as complex as a combination of values, variables and operators
• Expressions are often used to compute values or represent relationship between values

Example

“dev”     //”abc”
20         // 20
Var1 + Var2  // sum of Var1 and Var2
“Good” + “day”  //Good day
X <= Y && !Z    // true or false
myFun(a,b)  // function result

** Expressions can be used as arguments in function call.

Statements

• A statement is a complete unit of code that performs an action or operation.
• Statements are executable and may produce side effects, change the program’s state or control the flow of execution.
• A JavaScript program is essentially a sequence of statements executed one after another. The end of the statements are marked with semicolon.

let x = 5; // variable declaration statement
console.log(“Hello, World”); // Function call statement
if(x > 0){  // Conditional Statement
// code block can contain multiple statements and expressions
console.log(x)
}

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