Zepto源代码学习（一）

最近开始学习Zepto源代码，分享出来，共同学习。前端新人，技术欠佳，多多见谅
参考的gitbook地址
感谢作者奉献

代码主体机构：

定义Zepto——核心自执行函数 函数里面的变量都为私有变量，防止污染全局
var zepto = (function (){})(); 自执行函数
定义全局Zepto

核心函数 函数常用示例 $('div');

init函数：

    zepto.init = function (selector, context) {
        var dom
        // If nothing given, return an empty Zepto collection
        if (!selector) return zepto.Z()
        // Optimize for string selectors
        else if (typeof selector == 'string') {
            selector = selector.trim()
            // If it's a html fragment, create nodes from it
            // Note: In both Chrome 21 and Firefox 15, DOM error 12
            // is thrown if the fragment doesn't begin with <
            if (selector[0] == '<' && fragmentRE.test(selector))
                dom = zepto.fragment(selector, RegExp.$1, context), selector = null
            // If there's a context, create a collection on that context first, and select
            // nodes from there
            else if (context !== undefined) return $(context).find(selector)
            // If it's a CSS selector, use it to select nodes.
            else dom = zepto.qsa(document, selector)
        }
        // If a function is given, call it when the DOM is ready
        else if (isFunction(selector)) return $(document).ready(selector)
        // If a Zepto collection is given, just return it
        else if (zepto.isZ(selector)) return selector
        else {
            // normalize array if an array of nodes is given
            if (isArray(selector)) dom = compact(selector)
            // Wrap DOM nodes.
            else if (isObject(selector))
                dom = [selector], selector = null
            // If it's a html fragment, create nodes from it
            else if (fragmentRE.test(selector))
                dom = zepto.fragment(selector.trim(), RegExp.$1, context), selector = null
            // If there's a context, create a collection on that context first, and select
            // nodes from there
            else if (context !== undefined) return $(context).find(selector)
            // And last but no least, if it's a CSS selector, use it to select nodes.
            else dom = zepto.qsa(document, selector)
        }
        // create a new Zepto collection from the nodes found
        return zepto.Z(dom, selector)
    }

如果传递的第一个参数为string——首字母为< 并且时html标签 创建新的DOM
否则如果为正常的字符串直接获取DOM
如果有第二项参数 递归调用只有单参数本方法 并且执行find方法

如果传递的参数为函数——作为ready的回调传递

如果已经时zepto对象 直接返回

如果是DOM数组

如果是单个DOM

如果是html片段

返回一个执行的函数

zepto.Z函数：

// `$.zepto.Z` swaps out the prototype of the given `dom` array
    // of nodes with `$.fn` and thus supplying all the Zepto functions
    // to the array. This method can be overridden in plugins.
    zepto.Z = function (dom, selector) {
        return new Z(dom, selector)
    }

Z函数

function Z(dom, selector) {
        var i, len = dom ? dom.length : 0
        for (i = 0; i < len; i++) this[i] = dom[i]
        this.length = len
        this.selector = selector || ''
    }