代码改变世界

Webpack初试

2015-10-08 23:43  chen.simon  阅读(1988)  评论(0)  编辑  收藏  举报 
npm install -g webpack

老规矩，公司内网请设置代理：

npm config set proxy=http://127.0.0.1:8118

详细请参见官网 http://webpack.github.io/docs/tutorials/getting-started/

---------------------

1. 引用js

下面需要准备的文件的目录结构如下:

2015-10-09 09-54-46_webpack-demo_content.js － HBuilder

准备html页面  index.html

<html>
    <head>
        <meta charset="utf-8">
    </head>
    <body>
        <script type="text/javascript" src="bundle.js" charset="utf-8"></script>
    </body>
</html>

准备js

content.js

module.exports = "It works from content.js.";

entry.js

document.write(require("./content.js"));

用webpack命令编译,webpack命令的工作路径为entry.js所在路径：

webpack ./entry.js bundle.js

查看index.html便可以看到效果

2. 引用css

先安装loader,现在这个前端离开nodejs 还能玩么

用node安装需要的模块:

npm install css-loader style-loader
并在entry.js最上面加上如下代码:
require("!style!css!./style.css");

如果不想写前缀!style!css!,则对特定的文件扩展名指定特定的loader即可，下面是官网的详细介绍：

引用官网“

BINDING LOADERS

We don’t want to write such long requires require("!style!css!./style.css");.

We can bind file extensions to loaders so we just need to write: require("./style.css")

update entry.js
- require("!style!css!./style.css");

+ require("./style.css");

  document.write(require("./content.js"));

Run the compilation with:

webpack ./entry.js bundle.js --module-bind "css=style!css"

”

编译后的bundles.js代码解读:

主要思路就是用数组(第一次读数组，第二次直接取缓存)存放了各个模块,一个require调用算一个模块,require css是通过加处理css的util的函数生成,然后用这些js函数向dom中加入css内容.

 

/******/ (function(modules) { // webpackBootstrap
/******/     // The module cache
/******/     var installedModules = {};

/******/     // The require function
/******/     function __webpack_require__(moduleId) {

/******/         // Check if module is in cache
/******/         if(installedModules[moduleId])
/******/             return installedModules[moduleId].exports;

/******/         // Create a new module (and put it into the cache)
/******/         var module = installedModules[moduleId] = {
/******/             exports: {},
/******/             id: moduleId,
/******/             loaded: false
/******/         };

/******/         // Execute the module function
/******/         modules[moduleId].call(module.exports, module, module.exports, __webpack_require__);

/******/         // Flag the module as loaded
/******/         module.loaded = true;

/******/         // Return the exports of the module
/******/         return module.exports;
/******/     }


/******/     // expose the modules object (__webpack_modules__)
/******/     __webpack_require__.m = modules;

/******/     // expose the module cache
/******/     __webpack_require__.c = installedModules;

/******/     // __webpack_public_path__
/******/     __webpack_require__.p = "";

/******/     // Load entry module and return exports
/******/     return __webpack_require__(0);
/******/ })
/************************************************************************/
/******/ ([
/* 0 */
/***/ function(module, exports, __webpack_require__) {

    __webpack_require__(1);
    document.write(__webpack_require__(5));

/***/ },
/* 1 */
/***/ function(module, exports, __webpack_require__) {

    // style-loader: Adds some css to the DOM by adding a <style> tag

    // load the styles
    var content = __webpack_require__(2);
    if(typeof content === 'string') content = [[module.id, content, '']];
    // add the styles to the DOM
    var update = __webpack_require__(4)(content, {});
    if(content.locals) module.exports = content.locals;
    // Hot Module Replacement
    if(false) {
        // When the styles change, update the <style> tags
        if(!content.locals) {
            module.hot.accept("!!./node_modules/css-loader/index.js!./style.css", function() {
                var newContent = require("!!./node_modules/css-loader/index.js!./style.css");
                if(typeof newContent === 'string') newContent = [[module.id, newContent, '']];
                update(newContent);
            });
        }
        // When the module is disposed, remove the <style> tags
        module.hot.dispose(function() { update(); });
    }

/***/ },
/* 2 */
/***/ function(module, exports, __webpack_require__) {

    exports = module.exports = __webpack_require__(3)();
    // imports


    // module
    exports.push([module.id, "body {\r\n    background: yellow;\r\n}", ""]);

    // exports


/***/ },
/* 3 */
/***/ function(module, exports) {

    /*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
    */
    // css base code, injected by the css-loader
    module.exports = function() {
        var list = [];

        // return the list of modules as css string
        list.toString = function toString() {
            var result = [];
            for(var i = 0; i < this.length; i++) {
                var item = this[i];
                if(item[2]) {
                    result.push("@media " + item[2] + "{" + item[1] + "}");
                } else {
                    result.push(item[1]);
                }
            }
            return result.join("");
        };

        // import a list of modules into the list
        list.i = function(modules, mediaQuery) {
            if(typeof modules === "string")
                modules = [[null, modules, ""]];
            var alreadyImportedModules = {};
            for(var i = 0; i < this.length; i++) {
                var id = this[i][0];
                if(typeof id === "number")
                    alreadyImportedModules[id] = true;
            }
            for(i = 0; i < modules.length; i++) {
                var item = modules[i];
                // skip already imported module
                // this implementation is not 100% perfect for weird media query combinations
                //  when a module is imported multiple times with different media queries.
                //  I hope this will never occur (Hey this way we have smaller bundles)
                if(typeof item[0] !== "number" || !alreadyImportedModules[item[0]]) {
                    if(mediaQuery && !item[2]) {
                        item[2] = mediaQuery;
                    } else if(mediaQuery) {
                        item[2] = "(" + item[2] + ") and (" + mediaQuery + ")";
                    }
                    list.push(item);
                }
            }
        };
        return list;
    };


/***/ },
/* 4 */
/***/ function(module, exports, __webpack_require__) {

    /*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
    */
    var stylesInDom = {},
        memoize = function(fn) {
            var memo;
            return function () {
                if (typeof memo === "undefined") memo = fn.apply(this, arguments);
                return memo;
            };
        },
        isOldIE = memoize(function() {
            return /msie [6-9]\b/.test(window.navigator.userAgent.toLowerCase());
        }),
        getHeadElement = memoize(function () {
            return document.head || document.getElementsByTagName("head")[0];
        }),
        singletonElement = null,
        singletonCounter = 0;

    module.exports = function(list, options) {
        if(false) {
            if(typeof document !== "object") throw new Error("The style-loader cannot be used in a non-browser environment");
        }

        options = options || {};
        // Force single-tag solution on IE6-9, which has a hard limit on the # of <style>
        // tags it will allow on a page
        if (typeof options.singleton === "undefined") options.singleton = isOldIE();

        var styles = listToStyles(list);
        addStylesToDom(styles, options);

        return function update(newList) {
            var mayRemove = [];
            for(var i = 0; i < styles.length; i++) {
                var item = styles[i];
                var domStyle = stylesInDom[item.id];
                domStyle.refs--;
                mayRemove.push(domStyle);
            }
            if(newList) {
                var newStyles = listToStyles(newList);
                addStylesToDom(newStyles, options);
            }
            for(var i = 0; i < mayRemove.length; i++) {
                var domStyle = mayRemove[i];
                if(domStyle.refs === 0) {
                    for(var j = 0; j < domStyle.parts.length; j++)
                        domStyle.parts[j]();
                    delete stylesInDom[domStyle.id];
                }
            }
        };
    }

    function addStylesToDom(styles, options) {
        for(var i = 0; i < styles.length; i++) {
            var item = styles[i];
            var domStyle = stylesInDom[item.id];
            if(domStyle) {
                domStyle.refs++;
                for(var j = 0; j < domStyle.parts.length; j++) {
                    domStyle.parts[j](item.parts[j]);
                }
                for(; j < item.parts.length; j++) {
                    domStyle.parts.push(addStyle(item.parts[j], options));
                }
            } else {
                var parts = [];
                for(var j = 0; j < item.parts.length; j++) {
                    parts.push(addStyle(item.parts[j], options));
                }
                stylesInDom[item.id] = {id: item.id, refs: 1, parts: parts};
            }
        }
    }

    function listToStyles(list) {
        var styles = [];
        var newStyles = {};
        for(var i = 0; i < list.length; i++) {
            var item = list[i];
            var id = item[0];
            var css = item[1];
            var media = item[2];
            var sourceMap = item[3];
            var part = {css: css, media: media, sourceMap: sourceMap};
            if(!newStyles[id])
                styles.push(newStyles[id] = {id: id, parts: [part]});
            else
                newStyles[id].parts.push(part);
        }
        return styles;
    }

    function createStyleElement() {
        var styleElement = document.createElement("style");
        var head = getHeadElement();
        styleElement.type = "text/css";
        head.appendChild(styleElement);
        return styleElement;
    }

    function createLinkElement() {
        var linkElement = document.createElement("link");
        var head = getHeadElement();
        linkElement.rel = "stylesheet";
        head.appendChild(linkElement);
        return linkElement;
    }

    function addStyle(obj, options) {
        var styleElement, update, remove;

        if (options.singleton) {
            var styleIndex = singletonCounter++;
            styleElement = singletonElement || (singletonElement = createStyleElement());
            update = applyToSingletonTag.bind(null, styleElement, styleIndex, false);
            remove = applyToSingletonTag.bind(null, styleElement, styleIndex, true);
        } else if(obj.sourceMap &&
            typeof URL === "function" &&
            typeof URL.createObjectURL === "function" &&
            typeof URL.revokeObjectURL === "function" &&
            typeof Blob === "function" &&
            typeof btoa === "function") {
            styleElement = createLinkElement();
            update = updateLink.bind(null, styleElement);
            remove = function() {
                styleElement.parentNode.removeChild(styleElement);
                if(styleElement.href)
                    URL.revokeObjectURL(styleElement.href);
            };
        } else {
            styleElement = createStyleElement();
            update = applyToTag.bind(null, styleElement);
            remove = function() {
                styleElement.parentNode.removeChild(styleElement);
            };
        }

        update(obj);

        return function updateStyle(newObj) {
            if(newObj) {
                if(newObj.css === obj.css && newObj.media === obj.media && newObj.sourceMap === obj.sourceMap)
                    return;
                update(obj = newObj);
            } else {
                remove();
            }
        };
    }

    var replaceText = (function () {
        var textStore = [];

        return function (index, replacement) {
            textStore[index] = replacement;
            return textStore.filter(Boolean).join('\n');
        };
    })();

    function applyToSingletonTag(styleElement, index, remove, obj) {
        var css = remove ? "" : obj.css;

        if (styleElement.styleSheet) {
            styleElement.styleSheet.cssText = replaceText(index, css);
        } else {
            var cssNode = document.createTextNode(css);
            var childNodes = styleElement.childNodes;
            if (childNodes[index]) styleElement.removeChild(childNodes[index]);
            if (childNodes.length) {
                styleElement.insertBefore(cssNode, childNodes[index]);
            } else {
                styleElement.appendChild(cssNode);
            }
        }
    }

    function applyToTag(styleElement, obj) {
        var css = obj.css;
        var media = obj.media;
        var sourceMap = obj.sourceMap;

        if(media) {
            styleElement.setAttribute("media", media)
        }

        if(styleElement.styleSheet) {
            styleElement.styleSheet.cssText = css;
        } else {
            while(styleElement.firstChild) {
                styleElement.removeChild(styleElement.firstChild);
            }
            styleElement.appendChild(document.createTextNode(css));
        }
    }

    function updateLink(linkElement, obj) {
        var css = obj.css;
        var media = obj.media;
        var sourceMap = obj.sourceMap;

        if(sourceMap) {
            // http://stackoverflow.com/a/26603875
            css += "\n/*# sourceMappingURL=data:application/json;base64," + btoa(unescape(encodeURIComponent(JSON.stringify(sourceMap)))) + " */";
        }

        var blob = new Blob([css], { type: "text/css" });

        var oldSrc = linkElement.href;

        linkElement.href = URL.createObjectURL(blob);

        if(oldSrc)
            URL.revokeObjectURL(oldSrc);
    }


/***/ },
/* 5 */
/***/ function(module, exports) {

    module.exports = "It works from content.js.";

/***/ }
/******/ ]);

真正让css插入到html dom对象中的是 346行

调用栈如下：

2015-10-09 09-45-42_index.html

63-74行的代码压根不会起作用，不知道为什么会生成出来

整个代码的可读性不是很好

3.  编译进度条展示 加自动编译(auto build)

增加下面的选项即可：

webpack --progress --colors --watch

4.

部署到服务器…

 

5. 各种loader的支持

http://webpack.github.io/docs/list-of-loaders.html

如果是less的话 举例：

在js中加上

require("!style!css!less!./test.less");

end