130、common.js源码（非压缩版）

痛定思痛。 2023-06-05 08:22 36阅读 0赞

// 
    // CommonJS Client-side Implementation
    // 
    // Author: James Brumond <james@jbrumond.me> (http://www.jbrumond.me)
    // GitHub: https://www.github.com/UmbraEngineering/commonjs-preprocessor
    // 
    
    (function(window) {
    
        var head = document.getElementsByTagName('head')[0];
        
        // 
        // The core module loading function
        // 
        // @param {file} the module path to load
        // @param {from} the module requesting the require
        // 
        var require = window.require = function(file, from) {
            var module = require.lookup(file, from);
            if (! module) {
                var msg = 'Cannot find module "' + file + '"';
                if (from && from.filename) {
                    msg += ' in file "' + from.filename +  '"';
                }
                throw new Error(msg);
            }
            if (from) {
                from.children.push(module);
            }
            if (! module.loaded) {
                if (from) {
                    module.parent = from;
                }
                module.call();
            }
            return module.exports;
        };
    
        // 
        // Looks up and returns a module
        // 
        // @param {file} the module path to load
        // @param {from} the module requesting the lookup
        // 
        require.lookup = function(file, from) {
            return require._modules[require.resolve(file, from)];
        };
    
        // 
        // Paths to search for non-relative modules. By default, that just
        // looks them up from the root JavaScript directory. These should
        // all begin with a slash "/".
        // 
        require.paths = [ '/' ];
    
        // 
        // The JavaScript source directory, used by {require.load}. If the common.js
        // client is not in the root JavaScript directory, this should be overriden
        // to be accurate.
        // 
        require.dir = (function() {
            var script = document.getElementsByTagName('script');
            script = script[script.length - 1];
            var src = script.getAttribute('src');
            script = null;
            src = src.split('/');
            src.pop();
            return src.join('/');
        }());
    
        // 
        // Resolves a given {file} path and {from} module to get an exact
        // lookup path for the requested module
        // 
        // @param {file} the module path to load
        // @param {from} the module requesting the resolve
        // 
        require.resolve = function(file, from) {
            if (file.slice(-3) !== '.js') {
                file += '.js';
            }
    
            switch (file.charAt(0)) {
                // Absolute path (relative to given JavaScript root directory)
                //   eg. require('/module');
                case '/':
                    return modulePath(file);
                break;
                
                // Relative path
                //   eg. require('./module');
                case '.':
                    file = file.split('/');
                    
                    var dir = from ? from.dirname : '';
                    var segments = dir.split('/');
                    
                    for (var i = 0, c = file.length; i < c; i++) {
         
                        switch (file[i]) {
                            case '.': /* pass */ break;
                            case '..': segments.pop(); break;
                            default: segments.push(file[i]); break;
                        }
                    }
    
                    file = segments.join('/');
                    return modulePath(file);
                break;
                
                // Just module name
                //   eg. require('module');
                default:
                    for (var i = 0, c = require.paths.length; i < c; i++) {
         
                        var dir = require.paths[i];
                        if (dir.charAt(dir.length - 1) !== '/') {
                            dir += '/';
                        }
                        var resolved = dir + file;
                        if (resolved = modulePath(resolved)) {
                            return resolved;
                        }
                    }
                    return null;
                break;
            }
    
            function modulePath(file) {
                if (require.exists(file)) {
                    return file;
                }
    
                file = file.slice(0, -3) + '/index.js';
    
                if (require.exists(file)) {
                    return file;
                }
    
                return null;
            }
        };
    
        // 
        // Loads a JavaScript file async if it is not already loaded. The given
        // {files} must be absolute paths.
        // 
        // @param {files...} the files to load
        // 
        require.load = function() {
            var promise = require.load.defer();
            var files = Array.prototype.slice.call(arguments);
            var toLoad = files.length;
    
            // Iterate through the files and load each one
            for (var i = 0, c = files.length; i < c; i++) {
         
                var file = files[i];
    
                if (file.charAt(0) !== '/') {
                    file = '/' + file;
                }
    
                file = require.dir + file;
    
                if (file.slice(-3) !== '.js') {
                    file += '.js';
                }
    
                // Create the script tag
                var script = require.load.createScript({
                    src: file,
                    defer: true,
                    async: true
                });
    
                // Set an onload handler
                script.onload = script.onreadystatechange = function() {
                    if (! script.readyState || script.readyState === 'loaded' || script.readyState === 'complete') {
                        // Cleanup
                        script.onload = script.onreadystatechange = null;
                        if (head && script.parentNode) {
                            head.removeChild(script);
                        }
    
                        // Mark the file as loaded and check if we are done
                        if (! --toLoad) {
                            promise.resolve();
                        }
                    }
                };
    
                // Inject the script
                head.appendChild(script);
            }
    
            return promise;
        };
    
        // 
        // Create a deferred
        // 
        require.load.defer = function() {
            var promise = {
                funcs: [ ],
                passed: false,
                then: function(func) {
                    if (promise.passed) {
                        setTimeout(func, 0);
                    } else {
                        promise.funcs.push(func);
                    }
                },
                resolve: function() {
                    promise.passed = true;
                    for (var i = 0, c = promise.funcs.length; i < c; i++) {
         
                        setTimeout(promise.funcs[i], 0);
                    }
                }
            };
    
            return promise;
        };
    
        // 
        // Check if a list of files has been loaded
        // 
        // @param {files} a list of module files to check on
        // 
        require.loaded = function(files) {
            var loaded = true;
            for (var i = 0, c = files.length; i < c; i++) {
         
                if (! require.resolve(files[i])) {
                    loaded = false;
                    break;
                }
            }
            return loaded;
        };
    
        // 
        // This is where modules are stored
        // 
        // require._modules[*] = {
        //   loaded: Bool,
        //   exports: Mixed,
        //   filename: String,
        //   require: Function,
        //   parent: module,
        //   children: [module],
        //   call: Function
        // }
        // 
        require._modules = { };
    
        // 
        // Determine if the given module exists. We use {hasOwnProperty} here to be extra
        // careful, but it should never actually be an issue as all of the module property
        // names should begin with a slash, and if anyone is defining new prototype properties
        // that start with a slash, they deserve what is coming to them...
        // 
        // @param {file} an absolute module path
        // 
        require.exists = (require._modules.hasOwnProperty
            ? function(file) {
                return require._modules.hasOwnProperty(file);
            }
            : function(file) {
                return (file in require._modules[file]);
            });
    
        // 
        // Return a copy of {require} that is bound to the scope of a module. This is
        // used to create the copy store on modules at {module.require}.
        // 
        // @param {module} the module object to bind to
        // 
        require._bind = function(module) {
            var result = function(file, from) {
                return require(file, from || module);
            };
            result.lookup = function(file, from) {
                return require.lookup(file, from || module);
            };
            result.resolve = function(file, from) {
                return require.resolve(file, from || module);
            };
            result.load = function() {
                return require.load.apply(require, arguments);
            };
            result._modules = require._modules;
            return result;
        };
    
    }(window));

转载于:https://www.cnblogs.com/gushixianqiancheng/p/11259208.html