Trouble Understanding JQuery fundamentals

Can someone explain why in the below code, $(docume开发者_开发技巧nt).ready(function(){ $("#msgid").html(); }); must be called before I can append to the div with my appender function? If I get rid of that part, and press the button, nothing gets appended to the div, this doesn't make sense to me! I thought JQuery's .html() method just returned the HTML contents of the div, so in my below code it would return nothing, and therefore server no purpose.

CODE:

<script type="text/javascript">
$(document).ready(function(){  
    $("#msgid").html();        //WHY IS THIS CODE BLOCK NECESSARY?
    });

function appender(){
    $(document).ready(function(){
    $("#msgid").append("appended with the appender() function<br />");  
    });
}
</script>

This is Hello World by HTML

<div id="msgid">
</div>

<input type="button" id="myButton" value="click me" onclick=appender() />

Thanks in advance!

<script type="text/javascript">
    $(document).ready(function(){  
        $("#msgid").html("");        //This is to clear the html code that is inside #msgid
        });

    function appender(){
        $("#msgid").append("appended with the appender() function<br />");  
        });
    }
    </script>

    This is Hello World by HTML

    <div id="msgid">
    </div>

    <input type="button" id="myButton" value="click me" onclick=appender() />

Hope that helps

You do not need to have the $(document).ready() inside your function. But also, one of the main benefits of jQuery is its event handling, which allows you to stop using the onclick, onmouseoiver attributes in html.

Try:

    $(document).ready(function(){
        $("#msgid").click(function() {
//This function will be performed whenever the element with id msgid is clicked
 $("#msgid").append("appended by an anonymous function attached to the click event of this element");  
})
        });

OR

 $(document).ready(function(){
        $("#msgid").click('appender');
        });

    function appender()
    {
        $("#msgid").append("appended with the appender() function<br />");  
    }

Both will achieve the same end, but naming a function saves repeating code as always.

You can greatly simplify your code this way.

$(function() {
   $('#myButton').click(function() { 
       $("#msgid").append("appended with the appender() function<br />");
       return false;
   });
});

To do what you want , you can do as below

<script type="text/javascript">
$(document).ready(function(){  
    $("#msgid").html('');        //WHY IS THIS CODE BLOCK NECESSARY? to empty the contents of           the div

$("#msgid").click(function() {   
           appender();
        }); // end of click function
 }); // end of document.ready

The below functions behaves like a global function and you can call it from anywhere.

function appender(){        
    $("#msgid").append("appended with the appender() function<br />");          
}