6
It has become frequent for me to find codes on github that start like this:
;(function(window){
'use strict';
})();
Just never understood the following. What is the purpose of using the ';' before starting the function declaration?
2 answers
9
The semicolon is used to make sure that the previous instruction has been completed.
For example:
(function() {
})() // <--- Não tem ponto e vírgula
// Adicionado ponto e vírgula para evitar um resultado inesperado do código anterior
;(function ($) {
})();
The name of this technique is IIFE (Immediately-Invoked Function Expression).
-
1
Doing a search in English I found this here too: http://stackoverflow.com/questions/7145514/whats-the-purpose-of-starting-semi-colon-at-beginning-of-javascript Thanks for the answer! : D
8
Auto-summoning functions are built between parentheses, placing a semicolon before the start of the function can prevent the function from becoming part of any predecessor code, note that:
The code
var a = 10
(function(){...})()
Is the same as
var a = 10 (function(){...})()
Now putting the dot and comma, you avoid this kind of eventual problem in your code
var a = 10
;(function(){...})()
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2
Excellent addition. =)
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2
@Qmechanic73 noticed that you had already answered, but as I was already writing I took the opportunity to post :P
Browser other questions tagged javascript pattern-design
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It has the sources of these functions that originated the question?
– mutlei
https://github.com/fians/Waves/blob/master/src/js/waves.js This is an example...
– Pedro Vinícius
Related questions: http://answall.com/questions/38379/a-aus%C3%Aancia-de-ponto-e-v%C3%Adrgula-no-css-e-javascript-pode-influenciar-no-funcioname? lq=1, http://answall.com/questions/3341/utilizar-ou-n%C3%A3o-ponto-e-v%C3%Adrgula-no-fim-das-linhas-no-javascript
– bfavaretto