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Adam Sawicki
15,967 Pointsfunction definition vs expression
Hi,
Can someone explain to me what are best practices using function definition and expression? I mean when use which one and basic concepts.
Best Regards, Adam Sawicki
2 Answers
Steven Parker
231,007 PointsA function definition (also called a "function statement") exists as a complete statement, establishing a function with a specific name.
A function expression defines a function as a part of a larger expression syntax (typically a variable assignment or an argument passed to another function). Functions defined via expressions can be named or anonymous.
For more details, see these MDN pages on Function Statements and Function Expressions.
Adam Sawicki
15,967 PointsHi,
There are maybe guidelines/best practices where use which one ?
Best Regards, Adam
Steven Parker
231,007 PointsUsually, where you use it will make the choice for you. If you're passing a callback function as an argument, you will naturally create a function expression. If you're just defining a function to be called later in the program, you'd generally use a function statement. And sometimes it doesn't matter:
// these do exactly the same thing:
function logit(n) { console.log(n); } // function statement (perhaps easier to read)
var logit = function () { console.log(n); }; // assignment using function expression