🧠 Understanding JavaScript Execution and Data Types

When we write JavaScript code, every statement must follow the correct syntax. If the syntax is wrong, the compiler or the browser shows an error.
During execution, the JavaScript engine reads each expression and performs it step by step. This process happens in the runtime environment.

A variable can store any kind of value — a string, number, or boolean, and each of these is called a data type. When we create a variable using let or const, we perform an assignment. For example:

let age = 25;


Here, we assigned a number value to the variable age.

Some data in JavaScript are immutable, meaning they cannot be changed, like strings. Others are mutable, such as arrays and objects, which we can modify using methods like push() or pop().

When we work with data, we often need to filter, map, or loop through them using forEach. The map method creates a new array without changing the original one, while forEach usually causes a mutation, modifying existing data.

Understanding these concepts helps developers write clean, efficient, and bug-free code. Every function, loop, and variable plays an important role in the execution process of a program.

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