随机字符变换效果的jQuery插件开发教程

(function($){
    $.fn.shuffleLetters = function(prop){
        // Handling default arguments
        var options = $.extend({
            // Default arguments
        },prop)
        return this.each(function(){
            // The main plugin code goes here
        });
    };
    // A helper function
    function randomChar(type){
        // Generate and return a random character
    }
})(jQuery);

function randomChar(type){
    var pool = "";
    if (type == "lowerLetter"){
        pool = "abcdefghijklmnopqrstuvwxyz0123456789";
    }
    else if (type == "upperLetter"){
        pool = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    }
    else if (type == "symbol"){
        pool = ",.?/\(^)![]{}*&^%$#'"";
    }
    var arr = pool.split('');
    return arr[Math.floor(Math.random()*arr.length)];
}

$.fn.shuffleLetters = function(prop){

    var options = $.extend({
        "step"    : 8,    // How many times should the letters be changed
        "fps"    : 25,    // Frames Per Second
        "text"    : ""     // Use this text instead of the contents
    },prop)

    return this.each(function(){
        var el = $(this),
            str = "";
        if(options.text) {
            str = options.text.split('');
        }
        else {
            str = el.text().split('');
        }
        // The types array holds the type for each character;
        // Letters holds the positions of non-space characters;
        var types = [],
            letters = [];
        // Looping through all the chars of the string
        for(var i=0;ilen){
                return;
            }
            // All the work gets done here
            for(i=Math.max(start,0); i < len; i++){

                // The start argument and options.step limit
                // the characters we will be working on at once

                if( i < start+options.step){
                    // Generate a random character at this position
                    strCopy[letters[i]] = randomChar(types[letters[i]]);
                }
                else {
                    strCopy[letters[i]] = "";
                }
            }
            el.text(strCopy.join(""));
            setTimeout(function(){
                shuffle(start+1);
            },1000/options.fps);
        })(-options.step);
    });
};