Chrome插件開發，美化網頁上的文件列表。chrome-extension，background

時間 2019-11-07

標籤 chrome 插件開發美化網頁文件列表 extension background 欄目 Chrome 简体版

原文原文鏈接

上一篇文章經過「content-scripts」的方式向頁面注入js和css來美化頁面，可是有一個弊端：一旦配置好須要注入的頁面，以後若是這個頁面地址之後發生變化，或者要新加一些URL進來，那麼得修改manifest.json這個文件。試想若是一個Chrome插件已經打包好，再去改代碼是不可能的。javascript

本文經過另外一種方式來實現相同的功能，同時作到頁面地址動態可配置。下圖是本次要處理的頁面：https://jiacrontab.iwannay.cn/download/css

每一行都是一個文件的基本信息，包括文件名、日期和文件大小，文件名格式統一爲：項目名-版本-操做系統-平臺（分類要大於等於三個，用「-」分隔，這是使用本插件的前提）。如今文件還少，查看不是很困難，若是之後文件多了，那麼找一個文件是比較困難的。html

這裏又不太可能在服務端讀取download目錄下的文件，而後分類、分頁展現，那隻能在客戶端瀏覽器上想辦法了，Chrome插件能夠實現這個功能。java

1、小試牛刀

開發Chrome插件第一步，新建一個manifest.json文件，並按官方文檔的要求配置一些必要參數node

{
  "name": "WebFileFilterPro",
  "version": "1.0.0",
  "description": "fast sort your webpage files",
  "icons": {
    "16": "images/16.png",
    "48": "images/48.png",
    "128": "images/128.png"
  },
  "browser_action": {
    "default_icon": "images/16.png",
    "default_title": "WebFileFilterPro"
  },
  "manifest_version": 2
}

name：插件名稱react

version：版本號jquery

description：插件描述git

icons：圖標，不一樣尺寸用於不一樣地方github

browser_action：右上角插件欄的圖標信息，包括：圖標的圖片路徑、鼠標劃上去提示的文字web

manifest_version：固定爲2

注：更多manifest.json的配置參考：官方文檔看看如今的項目結構

一個簡單的沒有任何功能的Chrome插件就完成了，去Chrome瀏覽器裏安裝下試試：打開Chrome瀏覽器 - 更多工具 - 擴展程序，打開「開發者模式」 - 加載已解壓的擴展程序 - 選擇src目錄 - 肯定

由圖可見，manifest.json裏配置的插件名稱、版本號、插件描述等信息都體現了

2、加大難度

本插件的目的就是向特定頁面注入一些js和css文件，達到美化頁面的效果。如今來新建一個配置頁面

把須要美化的頁面地址經過配置頁面保存到Local Storage瀏覽器緩存裏面，這樣作的好處是：須要美化的地址隨時可變，同時發現須要美化的頁面直接加進去就能夠了，不用修改代碼。

這個時候大殺器「background」就要出場了，官方描述是這樣的

Extensions are event based programs used to modify or enhance the Chrome browsing experience. Events are browser triggers, such as navigating to a new page, removing a bookmark, or closing a tab. Extensions monitor these events in their background script, then react with specified instructions.

大體意思是，「background」是常駐Chrome瀏覽器後臺運行的，能夠捕獲到不少行爲：頁面跳轉、移除書籤、關閉一個tab頁等等。這裏不須要那麼強大的功能，只須要獲取用戶打開的頁面地址，是否是在配置頁面配置的地址便可。

如今改下「manifest.json」文件，加入新的配置

{
  "name": "WebFileFilterPro",
  "version": "1.0.0",
  "description": "fast sort your webpage files",
  "icons": {
    "16": "images/16.png",
    "48": "images/48.png",
    "128": "images/128.png"
  },
  "browser_action": {
    "default_icon": "images/16.png",
    "default_title": "WebFileFilterPro"
  },
  "options_page": "settings.html",
  "permissions": [
    "tabs",
    "http://*/*",
    "https://*/*"
  ],
  "background": {
    "scripts": [
      "js/background.js"
    ],
    "persistent": false
  },
  "manifest_version": 2
}

options_page：配置頁面地址（右鍵右上角插件圖標，能夠經過「選項」進入配置頁面）

background：後臺配置，包括js文件名和持久性設置

permissions：申請權限列表

1）tabs：獲取用戶訪問頁面得URL地址，必須得有tabs權限

2）http/https：向目標頁面裏注入css和js文件須要的權限

注：完整權限api請訪問：Declare Permissions

如今來看下官方說的能夠常駐後臺運行的「background.js」到底能夠獲取到哪些東西

chrome.tabs.onUpdated.addListener(function (tabId, changeInfo, tab) {
    if (changeInfo.status == "complete") {
        var url = tab.url;
        console.log("用戶訪問：" + url);

        console.log("緩存裏設置的頁面：" + localStorage.url);
    };
});

在頁面首次打開或者刷新事件（onUpdated）裏獲取「用戶訪問的頁面地址」和「配置頁面裏面配置的地址」，看看控制檯輸出

兩個地址都正確的獲取到了，若是用戶訪問的地址和配置的地址吻合，那麼向這個頁面注入css和js文件

chrome.tabs.onUpdated.addListener(function (tabId, changeInfo, tab) {
    if (changeInfo.status == "complete") {
        var url = tab.url;
        console.log(url);

        if (localStorage.url != undefined && localStorage.url != '') {
            var urlList = localStorage.url.split("\n");

            if (urlList.indexOf(url) != -1) {
                chrome.tabs.insertCSS(tabId, { file: "css/bootstrap.min.css" });

                chrome.tabs.executeScript(tabId, { file: "js/jquery.min.js" });
                chrome.tabs.executeScript(tabId, { file: "js/bootstrap.min.js" });                
                chrome.tabs.executeScript(tabId, { file: "js/filelist.js" });
            }
        }
    };
});

使用「chrome.tabs.insertCSS」和「chrome.tabs.executeScript」這兩個api完成css和js的注入。有了jQuery和Bootstrap的注入，頁面就能夠隨意美化了。「filelist.js"代碼以下

//console.log("filelist.js");

var fileList = [];
var preList = document.getElementsByTagName("pre");
if (preList.length == 1) {
    var lineList = preList[0].innerHTML.split("\n");
    //console.log(lineList);
    if (lineList.length > 0) {
        var splitLinetext = []; var splitFileName = []; var fileName = '';
        $.each(lineList, function (i, v) {
            //console.log(v);
            if (i == 0) {
                return true;//continue;
            }
            if (v == undefined || v == "") {
                var line = parseInt(i);
                line += 1;
                console.log("line:" + line + " is empty");
                return true;
            }

            splitLinetext = v.split(/\s+/);
            if (splitLinetext.length != 5) {
                console.log(splitLinetext);
                return true;
            }

            fileName = splitLinetext[1].match(/>(\S*)</)[1];
            //console.log(fileName);
            if (fileName == null || fileName == '') {
                console.log("fileName is or empty");
                return true;
            }

            splitFileName = fileName.split('-');
            if (splitFileName.length < 3) {
                console.log(splitFileName);
                return true;
            }

            fileList.push({ PartA: splitFileName[0], PartB: splitFileName[1], FileTime: formatDate(splitLinetext[2] + ' ' + splitLinetext[3]), FileSize: splitLinetext[4], FileName: fileName });
        });
        //console.log(fileList);

        var nodeDoctype = document.implementation.createDocumentType('html', '', '');
        if (document.doctype) {
            document.replaceChild(nodeDoctype, document.doctype);
        } else {
            document.insertBefore(nodeDoctype, document.childNodes[0]);
        }

        $("html").attr("lang", "en");
        $("head").html('<head><meta charset="UTF-8"><link rel="shortcut icon" href="" /><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta http-equiv="X-UA-Compatible" content="ie=edge"><title>FileList</title></head>');

        $("[rel='shortcut icon']").attr("href", chrome.extension.getURL("images/16.png"));

        $("body").removeAttr("bgcolor").html('<nav class="navbar navbar-default navbar-static-top"><div class="container"><div class="row"><div class="col-sm-2 col-md-2 col-lg-2"></div><div class="col-sm-10 col-md-10 col-lg-10"><div class="navbar-header"><button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar"><span class="sr-only">Toggle navigation</span><span class="icon-bar"></span><span class="icon-bar"></span><span class="icon-bar"></span></button></div><div id="navbar" class="collapse navbar-collapse"><ul class="nav navbar-nav"></ul></div></div></div></div></nav><div class="container"><div class="row"><div id="nav" class="col-sm-2 col-md-2 col-lg-2"><ul class="nav nav-pills nav-stacked"></ul></div><div class="col-sm-10 col-md-10 col-lg-10"><table id="table" class="table table-bordered"></table><ul class="pager"><span id="pageIndexSpan"></span>&nbsp;/&nbsp;<span id="pageSizeSpan"></span>&nbsp;/&nbsp;<span id="totalCountSpan"></span>&nbsp;&nbsp;<li id="previousPageLi"><a href="javascript:;">Prev</a></li>&nbsp;<li id="nextPageLi"><a href="javascript:;">Next</a></li></ul></div></div></div>');

        var partAs = getDistinctPartA();
        $.each(partAs, function (idx, val) {
            $("#navbar ul").append("<li data-value=\"" + val + "\"><a href='javascript:;'><strong>" + val + "</strong></a></li>");
        });
        if (partAs.length > 0) {
            if (localStorage.partA != undefined && $.inArray(localStorage.partA, partAs) != -1)
                navBarLiClick(localStorage.partA);
            else
                navBarLiClick(partAs[0]);
        }
        else {
            $("body").html('<div class="container"><div class="row"><div class="col-sm-12 col-md-12 col-lg-12"><h3>no data, pls wait and refresh this page :)</h3></div></div></div>');
        }
    }
    else {
        console.log("can't find any line in <pre> tag");
    }
}
else {
    console.log("page's <pre> tag count illegal:" + preList.length);
}

$("body").on("click", "#navbar ul li", function () {
    navBarLiClick($(this).attr("data-value"));
});

$("body").on("click", "#nav ul li", function () {
    navLiClick($(this).attr("data-parta"), $(this).attr("data-partb"));
});

$("body").on("click", "#table tbody tr", function () {
    $(this).css("background", "#DCDCDC").siblings().css("background", "");
});

$("body").on("click", "#previousPageLi", function () {
    if (localStorage.pageIndex != 1) {
        localStorage.pageIndex = parseInt(localStorage.pageIndex) - 1;
        initFileList(localStorage.partA, localStorage.partB);
    }
});

$("body").on("click", "#nextPageLi", function () {
    var totalPageCount = localStorage.totalCount % localStorage.pageSize == 0 ? localStorage.totalCount / localStorage.pageSize : Math.ceil(localStorage.totalCount / localStorage.pageSize);
    if (localStorage.pageIndex != totalPageCount) {
        localStorage.pageIndex = parseInt(localStorage.pageIndex) + 1;
        initFileList(localStorage.partA, localStorage.partB);
    }
});

function formatDate(dt) {
    var date = new Date(dt);
    var aaaa = date.getFullYear();
    var gg = date.getDate();
    var mm = (date.getMonth() + 1);

    if (gg < 10) gg = "0" + gg;
    if (mm < 10) mm = "0" + mm;

    var cur_day = aaaa + "-" + mm + "-" + gg;
    var hours = date.getHours()
    var minutes = date.getMinutes()
    //var seconds = date.getSeconds();

    if (hours < 10) hours = "0" + hours;
    if (minutes < 10) minutes = "0" + minutes;
    //if (seconds < 10) seconds = "0" + seconds;

    //return cur_day + " " + hours + ":" + minutes + ":" + seconds;
    return cur_day + " " + hours + ":" + minutes;
}

function getDistinctPartA() {
    return JSLINQ(fileList).Distinct(function () { return this.PartA; }).items;
}

function getDistinctPartB(partA) {
    return JSLINQ(fileList).Where(function () { return this.PartA == partA; }).Distinct(function () { return this.PartB; }).items;
}

function getFileListPage(partA, partB) {
    var totalPageCount = localStorage.totalCount % localStorage.pageSize == 0 ? localStorage.totalCount / localStorage.pageSize : Math.ceil(localStorage.totalCount / localStorage.pageSize);

    if (localStorage.pageIndex == 1) {
        $("#previousPageLi").addClass("disabled");
    }
    else {
        $("#previousPageLi").removeClass("disabled");
    }
    if (localStorage.pageIndex == totalPageCount) {
        $("#nextPageLi").addClass("disabled");
    }
    else {
        $("#nextPageLi").removeClass("disabled");
    }

    $("#pageIndexSpan").text(localStorage.pageIndex);
    $("#pageSizeSpan").text(localStorage.pageSize);
    $("#totalCountSpan").text(localStorage.totalCount);

    if (partB == 'all') {
        return JSLINQ(fileList).Reverse().Where(function () { return this.PartA == partA; }).Skip(parseInt(localStorage.pageSize) * (parseInt(localStorage.pageIndex) - 1)).Take(parseInt(localStorage.pageSize)).Select("PartB,FileTime,FileSize,FileName").items;
    }
    else {
        return JSLINQ(fileList).Reverse().Where(function () { return this.PartA == partA && this.PartB == partB; }).Skip(parseInt(localStorage.pageSize) * (parseInt(localStorage.pageIndex) - 1)).Take(parseInt(localStorage.pageSize)).Select("PartB,FileTime,FileSize,FileName").items;
    }
}

function getFileListTotalCount(partA, partB) {
    if (partB == 'all') {
        return JSLINQ(fileList).Count(function () { return this.PartA == partA; });
    }
    else {
        return JSLINQ(fileList).Count(function () { return this.PartA == partA && this.PartB == partB; });
    }
}

function navBarLiClick(partA) {
    $("#navbar ul li[data-value=\"" + partA + "\"]").addClass("active").siblings().removeClass("active");

    $("#nav ul").empty();
    $("#nav ul").append("<li data-parta=\"" + partA + "\" data-partb=\"all\"><a href='javascript:;'>all</a></li>");

    var partB = '';
    var list = getDistinctPartB(partA);
    //list.sort();
    list.reverse();
    $.each(list, function (i, v) {
        if (localStorage.partB != undefined && localStorage.partA != undefined && localStorage.partA == partA && localStorage.partB == v) {
            partB = localStorage.partB;
            $("#nav ul").append("<li class='active' data-parta=\"" + partA + "\" data-partb=\"" + v + "\"><a href='javascript:;'>" + v + "</a></li>");
        }
        else {
            $("#nav ul").append("<li data-parta=\"" + partA + "\" data-partb=\"" + v + "\"><a href='javascript:;'>" + v + "</a></li>");
        }
    });
    if (partB == '') {
        partB = 'all';
        $("#nav ul li:first").addClass("active");
    }
    initFileList(partA, partB);
}

function navLiClick(partA, partB) {
    $("#nav ul li[data-partb=\"" + partB + "\"]").addClass("active").siblings().removeClass("active");
    initFileList(partA, partB);
}

function initFileList(partA, partB) {
    if (localStorage.partA != partA || localStorage.partB != partB) {
        localStorage.pageIndex = 1;
        localStorage.pageSize = 10;
    }

    if (localStorage.partA != partA) {
        localStorage.partA = partA;
    }
    if (localStorage.partB != partB) {
        localStorage.partB = partB;
    }

    var totalCount = getFileListTotalCount(partA, partB);
    if (localStorage.totalCount != totalCount) {
        localStorage.totalCount = totalCount;
    }

    var fileList = getFileListPage(partA, partB);

    $("#table").empty();
    // $("#table").append("<thead><tr><th>FileName</th><th>Time</th><th>FileSize</th><th>Operate</th></tr></thead><tbody>");
    if (fileList.length > 0) {
        $.each(fileList, function (i, v) {
            $("#table").append("<tr><td>" + v.FileName + "</td><td>" + v.FileTime + "</td><td>" + v.FileSize + "</td><td><a href='" + v.FileName + "' target='_blank'>Link</a></td></tr>");
        });
    }
    else {
        $("#table").append("<tr><td colspan='4'><center>no data</center></td></tr>");
    }
    $("#table").append("</tbody>");
}

View Code

獲取原頁面裏面的全部文件信息，項目名去重放在頂部，用Bootstrap的navBar插件展現，版本號由上到下依次放在左側的nav插件上，右側則用Bootstrap的table展現文件詳細信息。效果以下

至此，分類、翻頁展現功能完美實現，之後就算文件再多也能夠快速找到了。

3、總結

經過「background」的方式注入，優勢是頁面隨時能夠配置，很方便，缺點是用戶訪問的每一個頁面都須要在「background.js」裏面挨個過濾，感受效率不行。我的仍是比較喜歡「content_scripts」這種方式注入。

Chrome插件本地源碼路徑，方便學習其餘優秀插件的代碼：

1）windows xp：C:\Documents and Settings\用戶名\Local Settings\Application Data\Google\Chrome\User Data\Default\Extensions
2）windows xp+：C:\Users\用戶名\AppData\Local\Google\Chrome\User Data\Default\Extensions
3）MAC：~/Library/Application Support/Google/Chrome/Default/Extensions
4）Ubuntu：~/.config/google-chrome/Default/Extensions