JavaScript Console & JS Scope

Lecture Notes JAVASCRIPT CONSOLE ➢ What is Console? The console is an object in JavaScript which is used for debugging and logging results. ❖ All modern browsers have a web console for debugging.Console is a global object so it is available in every scope. ❖ It is also available in the global scope of the browser window. You can use it as window.console or direct console. ❖ Here we'll discuss some most used console methods. ➢ Console methods Console in javascript has several different methods. Among all the log method is most commonly used: Console.log() Mainly used to log the output to the console. We can put any type inside the log(), bet it a string, array, object etc. Console.table() It's allows us to generate a table inside a console. Console.count() It's used to count the number that the function hit by this counting method. Console.time() It's used to track how long does an operation takes to execute. JAVASCRIPT SCOPE ➢ Scope determines the accessibility (visibility) of variables, objects and functions. ➢ In JavaScript, a variable has 3 types of scope: o Block scope o Function scope o Global scope Block Scope Block scoping means declaring a variable inside the block or curly brackets {} can not be accessed from outside the block. NOTE: Variables declared with the var keyword can NOT have block scope. Function scope ❑ Function scoping means variables defined inside a function are not accessible from outside the function. ❑ Function scope is also known as local scope NOTE: Variables declared with var, let and const are quite similar when declared inside a function. Global Scope ➢ A variable declared at the top of a program or outside of a function is considered a global scope variable. ➢ In the program, variable a is a global variable. ➢ If you assign a value to a variable that has not been declared, it will automatically become a global variable. ➢ This code example will declared a global variable carName, even if the value is assigned inside a function