jquery extension example. Notice the use of chaining the styles together

extension-example.js

// creates a function that will add a 2px blue border around each div with the class "blue"
$.fn.blueBorder = function(){
    this.each(function(){
        $(this).css("border","solid blue 2px");
    });
    return this;
};

//creates a function that will turn the text color blue of each div 
$.fn.blueText = function(){
    this.each(function(){
        $(this).css("color","blue");
    });
    return this;
};

//on click, apply the functinos to EACH blue div
$("#b").click(function(){
    $('.blue').blueBorder().blueText();
});

index.html

<input id="b" type="button" value="Apply" /><br />
<div class="blue">1</div>
<div class="blue">2</div>
<div class="blue">3</div>