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Discussion on: A Simple Guide to JavaScript Functions - Native, Arrow and Shorthand.

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Replies for: I'm very new to JS, so I'm probably missing something, but is there an advantage to using a function expression instead of a regular function decla...

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codingnninja profile image
Ayobami Ogundiran • • Edited

I like this question because it feels like what I should have explained in the write-up.

Function expressions are not hoisted even when we use them with "var";

Thanks for raising the question.

The practical differences could be:

  1. We can't define or declare a regular functions in a conditional statement like if it is necessary to do so (but it is rarely necessary if not impossible), in that case we have to use function expression. 
(function() {
  'use strict';
  if (true) {
    function going() {
      return 'yes';
    }
  } else {
    function notGoing() {
      return 'no';
    }
  }
  console.log(typeof going === 'undefined'); // => true
  console.log(going()); // Throws "ReferenceError: going is not defined"
})();
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We will use function expression to make it work.

Note: Declaring a function in a conditional statement is not recommended or should be avoided.

2 . It is easy to pass a function expression around so it is used to create modules without worrying about polluting the global scope before the introduction of import and export.

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lucassperez profile image
Lucas Perez •

Thanks very much! Very nice text (: