What does function do

Question

Sometimes I make a function and call the function later   Example   function example   alert  example      example        lt -- Then call it later   Somehow  some functions cannot be called  I have to call those functions inside     function           What do   function        and  function         mean  and what s the difference purpose of these

User · Answer

I think you may be confusing Javascript with jQuery methods. Vanilla or plain Javascript is something like:

function example() {
}

A function of that nature can be called at any time, anywhere.

jQuery (a library built on Javascript) has built in functions that generally required the DOM to be fully rendered before being called. The syntax for when this is completed is:

$(document).ready(function() {
});

So a jQuery function, which is prefixed with the $ or the word jQuery generally is called from within that method.

$(document).ready(function() {        
    // Assign all list items on the page to be the  color red.  
    //      This does not work until AFTER the entire DOM is "ready", hence the $(document).ready()
    $('li').css('color', 'red');   
});

The pseudo-code for that block is:

When the document object model $(document) is ready .ready(), call the following function function() { }. In that function, check for all <li>'s on the page $('li') and using the jQuery method .CSS() to set the CSS property "color" to the value "red" .css('color', 'red');

User · Answer

Some Theory   is the name of a function like any other name you give to a function  Anyone can create a function in JavaScript and name it   as shown below      function              alert  I am in the   function           JQuery is a very famous JavaScript library and they have decided to put their entire framework inside a function named jQuery  To make it easier for people to use the framework and reduce typing the whole word jQuery every single time they want to call the function  they have also created an alias for it  That alias is    Therefore   is the name of a function  Within the jQuery source code  you can see this yourself  window jQuery   window     jQuery    Answer To Your Question So what is   function          Now that you know that   is the name of the function  if you are using the jQuery library  then you are calling the function named   and passing the argument function      into it  The jQuery library will call the function at the appropriate time  When is the appropriate time  According to jQuery documentation  the appropriate time is once all the DOM elements of the page are ready to be used  The other way to accomplish this is like this    document  ready function          As you can see this is more verbose so people prefer   function        So the reason why some functions cannot be called  as you have noticed  is because those functions do not exist yet  In other words the DOM has not loaded yet  But if you put them inside the function you pass to   as an argument  the DOM is loaded by then  And thus the function has been created and ready to be used  Another way to interpret   function        is like this  Hey   or jQuery  can you please call this function I am passing as an argument once the DOM has loaded

User · Answer

This is a shortcut for   document  ready    which is executed when the browser has finished loading the page  meaning here   when the DOM is available    See http   www learningjquery com 2006 09 introducing-document-ready  If you are trying to call example   before the browser has finished loading the page  it may not work

User · Answer

The following is a jQuery function call             Which is the  jQuery function     is a function  and        is you calling that function   The first parameter you ve supplied is the following   function        The parameter is a function that you specified  and the   function will call the supplied method when the DOM finishes loading

User · Answer

function               is just jQuery short-hand for     document  ready function               What it s designed to do  amongst other things  is ensure that your function is called once all the DOM elements of the page are ready to be used   However  I don t think that s the problem you re having - can you clarify what you mean by  Somehow  some functions are cannot be called and I have to call those function inside    Maybe post some code to show what s not working as expected    Edit  Re-reading your question  it could be that your function is running before the page has finished loaded  and therefore won t execute properly  putting it in   function  would indeed fix that

User · Answer

It s just shorthand for   document  ready    as in    document  ready function       YOUR CODE HERE      Sometimes you have to use it because your function is running before the DOM finishes loading   Everything is explained here  http   docs jquery com Tutorials Introducing   document  ready

[javascript] What does $(function() {} ); do?

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