The word “scope” itself means “extent “or “range” to which a subject matter is limited to. In context to coding this means, that whether you can use a variable or not, is determined by where it is declared in your code. There are 4 types of scope in a JavaScript document, for example script.js
1. Global scope
Inside a JavaScript document, global scope is the area outside any functions and blocks of code which are determined by the presence of opening and closing curly braces {}. For example:
//Global scope
function x() {
}
2. Local scope
Local scope refers to variables that are declared and/or assigned a value within a function.
function localScope() {
// local scope
}
3. Block scope
A block scope is defined as the area within curly braces {}. For example, if – else conditional statements, switch conditions, for and while loops and others.
{
//block scope
}4. Lexical scope
Within a function, any code blocks and child functions have access to the variables defined inside the main parent function’s scope. This is called lexical scope.
function parentScope() {
//variables declared here
function child() {
//variables can be accessed here
}
child();
}
