Difference between function expression vs declaration in JavaScript Last Updated : 22 Feb, 2023 Comments Improve Suggest changes Like Article Like Report Function Declaration: A Function Declaration( or a Function Statement) defines a function with the specified parameters without requiring a variable assignment. They exist on their own, i.e, they are standalone constructs and cannot be nested within a non-function block. A function is declared using the function keyword. Syntax:function gfg(parameter1, parameter2) { //A set of statements } Function Expression: A Function Expression works just like a function declaration or a function statement, the only difference is that a function name is NOT started in a function expression, that is, anonymous functions are created in function expressions. The function expressions run as soon as they are defined. Syntax:var gfg = function(parameter1, parameter2) { //A set of statements } Example 1: Using a Function Declaration javascript <!DOCTYPE html> <html> <head> <title>Function Declaration</title> </head> <body> <center> <h1 style="color:green">GeeksforGeeks</h1> <h3>Function Declaration</h3> <script> function gfg(a, b) { return a * b; } var result = gfg(5, 5); document.write(result); </script> </center> </body> </html> Output: 25 Example 2: Using a Function Expression javascript <!DOCTYPE html> <html> <head> <title>Function Expression</title> </head> <body> <center> <h1 style="color:green">GeeksforGeeks</h1> <h3>Function Expression</h3> <script> var gfg = function(a, b) { return a * b; } document.write(gfg(5, 5)); </script> </center> </body> </html> Output: 25 Comment More infoAdvertise with us Next Article Difference between function expression vs declaration in JavaScript N Nilarjun Follow Improve Article Tags : Difference Between JavaScript Web Technologies Web Technologies - Difference Between Similar Reads Difference between ‘function declaration’ and ‘function expression' in JavaScript Functions in JavaScript allow us to carry out some set of actions, important decisions, or calculations and even make our website more interactive. 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