Scope is the set of variables you have access to.
In JavaScript, objects and functions, are also variables.
In JavaScript, scope is the set of variables, objects, and functions you have access to.
JavaScript has function scope: The scope changes inside functions.
Variables declared within a JavaScript function, become LOCAL to the function.
Local variables have local scope: They can only be accessed within the function.
Since local variables are only recognized inside their functions, variables with the same name can be used in different functions.
Local variables are created when a function starts, and deleted when the function is completed.
A variable declared outside a function, becomes GLOBAL.
A global variable has global scope: All scripts and functions on a web page can access it.
If you assign a value to a variable that has not been declared, it will automatically become a GLOBAL variable.
This code example will declare carName as a global variable, even if it is executed inside a function.
The lifetime of a JavaScript variable starts when it is declared.
Local variables are deleted when the function is completed.
Global variables are deleted when you close the page.
Function arguments (parameters) work as local variables inside functions.
With JavaScript, the global scope is the complete JavaScript environment.
In HTML, the global scope is the window object: All global variables belong to the window object.
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Your global variables, or functions, can overwrite window variables or
functions. Anyone, including the window object, can overwrite your global variables or functions. |
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