随机字符转换效果的jQuery插件开发教程

随机字符变换效果的jQuery插件开发教程

来源：tutorialzine.com???????? 编译：GBin1.com

?

在这篇快速的jQuery插件开发教程中，我们将创建一个jQuery插件用来随机排序显示任何一个DOM元素的文字内容 -这将会是一个非常有趣的效果，可以用在标题，logo及其幻灯效果中。

?

?

在线演示?????? 在线下载

?

那么第一部呢，我们将开发jQuery插件的基本架构。我们将把代码放入一个自运行的方法中，并且扩展$.fn.

(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);

下一步我们将关注与randomChar()方法。它将会接受一个类型参数（Lowerletter, upperletter或者symbol），并且返回一个随机字符。

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)];}

我们本应该使用一个简单的字符池来保存所有的字符，但是这样会有更好效果。

现在我们来书写插件的body部分：

$.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;i<str.length;i++){?? ??? ??? ?var ch = str[i];?? ??? ??? ?if(ch == " "){?? ??? ??? ??? ?types[i] = "space";?? ??? ??? ??? ?continue;?? ??? ??? ?}?? ??? ??? ?else if(/[a-z]/.test(ch)){?? ??? ??? ??? ?types[i] = "lowerLetter";?? ??? ??? ?}?? ??? ??? ?else if(/[A-Z]/.test(ch)){?? ??? ??? ??? ?types[i] = "upperLetter";?? ??? ??? ?}?? ??? ??? ?else {?? ??? ??? ??? ?types[i] = "symbol";?? ??? ??? ?}?? ??? ??? ?letters.push(i);?? ??? ?}?? ??? ?el.html("");?? ??? ??? ??? ??? ?// Self executing named function expression:?? ??? ?(function shuffle(start){?? ??? ??? ?// This code is run options.fps times per second?? ??? ??? ?// and updates the contents of the page element?? ??? ??? ?var i,?? ??? ??? ??? ?len = letters.length,?? ??? ??? ??? ?strCopy = str.slice(0);?? ?// Fresh copy of the string?? ??? ??? ?if(start>len){?? ??? ??? ??? ?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);?? ?});};

这个插件将可以接受被调用的DOM元素的内容，或者当作一个参数传入的对象的text属性。然后它分割字符串到字符，并且决定使用的类型。这个shuffle功能使用setTimeout()来调用自己并且随机生成字符串，更新DOM元素。如果你不清楚setTimeout()的使用，可以参考这篇文章：http://www.gbin1.com/technology/jqueryhowto/fadeoutonebyone/ ，?调用seTimeout方法可以帮助你按特定时间间隔执行某些操作。

?

原文来自：随机字符变换效果的jQuery插件开发教程