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 = "abcdefghijklmnopqrstuvwxyz01234567";
 }
 else if (type == "upperLetter"){
 pool = "ABCDEFGHIJKLMNOPQRSTUVWXYZ01234567";
 }
 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);
 });
};