There's no real difference; both will return undefined. Functions with no return statement will return undefined, as will functions with an empty return statement. To confirm this for yourself, you can run this code -- FIDDLE: function a() { return;

Feb 5, 2014 · The difference is that a() calls the function while a is the function. console.log( a() ); // false console.log( a ); // function() {...} To make it clear what technically happens when you use the second part of your example, let's redefine alike this: a = function() { return 100; }; and set the event handler: anything.onclick = a();

Aug 4, 2023 · without the parentheses you are assigning the function itself ( functions are first class objects ) whereas with the parentheses you are executing the function and assigning the resultant value.

Aug 4, 2020 · If you don't use parentheses, you're not calling the function. Instead you use its name, just like you would use a variable name for a string or a number. The addEventListener method expects a function, not a function call. The call will happen automatically based on …

Mar 7, 2025 · The statements following the with statement refer to the PI property and the cos and sin methods, without specifying an object. JavaScript assumes the Math object for these references.

Jun 10, 2020 · If the code needs to execute only one of two things (or a few things) use an if else (or a switch). If you only need to guard a single thing, use an if. The code in the original post works because the if clause returns.

【JavaScript function calls with and without parentheses】 Without parentheses, the function name is used as the pointer of the function. The name of a function is the pointer of the function. At this time, the result of the function is not obtained, because the …

Jun 25, 2019 · You can call the same function with ‘new’ keyword and without ‘new’ keyword. You can call the same function through an object and not through an object. How you call the function matters a lot and JavaScript would provide completely different results in each scenario.

May 21, 2024 · To summarize, the key difference between passing a function reference with and without parentheses when setting up an event listener in JavaScript is that without parentheses, you pass the function itself to be executed later when the event occurs, while with parentheses, you execute the function immediately and pass its return value, which is ...

Oct 1, 2015 · With declaration, it is required to write an identifier which in this case is withName. Both the example that you have given are of function expression where it is not required to write the identifier i.e. withName as you can still call this function with the variable x or y.