利用localStorage储存js文件，只有在第一次访问该页面的时候加载js文件，以后在访问的时候加载本地localStorage执行

封装lsFile类 有url、filename（key前缀）、lname（key）、filetext（值）属性

var lstorage = window.localStoragefunction lsFile(url){    this.url = url    this.filename = url.substring(url.lastIndexOf("/")+1,url.lastIndexOf("."))    //this.filename  = document.location.pathname    this.lname     = 'Lsf_'+this.filename+'_'+url.substring(url.lastIndexOf("?")+1)    this.filetext    = lstorage.getItem(this.lname)    this.init()}

首先判断本地localStorage有没有缓存文件，有的话直接getItem获取，通过eval执行，没有话通过执行ajax获取js文件内容。

lsFile.prototype.init = function(){    if (this.filetext){        this.eval(this.filetext)    }else{        this.xhr(this.url,this.runstr)    }}

通过ajax采用同步的形式获取js内容，取得内容后，eval执行js文件的内容，setItem设置保存到localStorage中，再删除localStorage中上个版本的文件。

lsFile.prototype.runstr = function(filetext){    this.eval(filetext)    lstorage.setItem(this.lname,filetext)       this.removels()}

ajax同步获取js文件内容。

lsFile.prototype.xhr = function(url,callback){    var _this = this    var version = url.substring(url.lastIndexOf("?"))    var xhr = new XMLHttpRequest();    xhr.onreadystatechange = function(){        switch(xhr.readyState){            case 4:                if(xhr.status==200){                    var filetext = xhr.responseText                    if(callback){                        callback.call(_this,filetext)                    }                }else{                    alert('加载失败')                }                break;            default:                break;        }    }    xhr.open('GET',url,false);    xhr.send();}

删除localStorage中上个版本的文件方法，通过名字规则查找，除了当前设置的名字的之外有相同前缀的，通过removeItem删除。

lsFile.prototype.removels = function(){    var arr = []    for(var i=0;i
    
      -1 && name != this.lname){            arr.push(name)        }    }    for(var i in arr){        localStorage.removeItem(arr[i]);    }}
    

使用

lsFile('/demo/lsfile/zepto.js?20150620')

移动端webapp使用

以下是完整代码

!function(w){    'use strict'    var lstorage = window.localStorage        function lsFile(url){        this.url = url        this.filename = url.substring(url.lastIndexOf("/")+1,url.lastIndexOf("."))        //this.filename  = document.location.pathname        this.lname     = 'Lsf_'+this.filename+'_'+url.substring(url.lastIndexOf("?")+1)        this.filetext    = lstorage.getItem(this.lname)        this.init()    }    lsFile.prototype.init = function(){        if (this.filetext){            this.eval(this.filetext)        }else{            this.xhr(this.url,this.runstr)        }    }    lsFile.prototype.xhr = function(url,callback){        var _this = this        var version = url.substring(url.lastIndexOf("?"))        var xhr = new XMLHttpRequest();        xhr.onreadystatechange = function(){            switch(xhr.readyState){                case 4:                    if(xhr.status==200){                        var filetext = xhr.responseText                        if(callback){                            callback.call(_this,filetext)                        }                    }else{                        alert('加载失败')                    }                    break;                default:                    break;            }        }        xhr.open('GET',url,false);        xhr.send();    }    lsFile.prototype.runstr = function(filetext){        this.eval(filetext)        lstorage.setItem(this.lname,filetext);        this.removels()    }    lsFile.prototype.removels = function(){        var arr = []        for(var i=0;i
    
      -1 && name != this.lname){                arr.push(name)            }        }        for(var i in arr){            localStorage.removeItem(arr[i]);        }    }        lsFile.prototype.eval = function(filetext){        window.eval(filetext)    }    w.lsFile = function (url){        return new lsFile(url)    }}(window)