• 打算从头梳理一次vue.js,用的是vue.js很早之前的版本，学习起来应该困难没那么大，持续更新

整体分析

;(function(){
    //17-52定义require方法
    function require() {}

    //定义require属性和方法 58-211
    require.modules = {}; ……

    //注册模块，引用对象  ，后面注册模块如下图
    require.register('vue/src/main.js', function() {

    });

 

})();

// 后面注册模块源码

1.png

2.png

require对象 17-210行

• 使用场景： 如：require('./utils')

function require(path, parent, orig) {
  var resolved = require.resolve(path);

  // lookup failed
  if (null == resolved) {
    throwError()
    return
  }

  var module = require.modules[resolved];

  // perform real require()
  // by invoking the module's
  // registered function
  if (!module._resolving && !module.exports) {
    var mod = {};
    mod.exports = {};
    mod.client = mod.component = true;
    module._resolving = true;
    module.call(this, mod.exports, require.relative(resolved), mod);
    delete module._resolving;
    module.exports = mod.exports;
  }

  function throwError () {
    orig = orig || path;
    parent = parent || 'root';
    var err = new Error('Failed to require "' + orig + '" from "' + parent + '"');
    err.path = orig;
    err.parent = parent;
    err.require = true;
    throw err;
  }

  return module.exports;
}

/**
 * Registered modules.
 */

require.modules = {};

/**
 * Registered aliases.
 */

require.aliases = {};

/**
 * Resolve `path`.
 *
 * Lookup:
 *
 *   - PATH/index.js
 *   - PATH.js
 *   - PATH
 *
 * @param {String} path
 * @return {String} path or null
 * @api private
 */

require.exts = [
    '',
    '.js',
    '.json',
    '/index.js',
    '/index.json'
 ];

require.resolve = function(path) {
  if (path.charAt(0) === '/') path = path.slice(1);

  for (var i = 0; i < 5; i++) {
    var fullPath = path + require.exts[i];
    if (require.modules.hasOwnProperty(fullPath)) return fullPath;
    if (require.aliases.hasOwnProperty(fullPath)) return require.aliases[fullPath];
  }
};

/**
 * Normalize `path` relative to the current path.
 *
 * @param {String} curr
 * @param {String} path
 * @return {String}
 * @api private
 */

require.normalize = function(curr, path) {

  var segs = [];

  if ('.' != path.charAt(0)) return path;

  curr = curr.split('/');
  path = path.split('/');

  for (var i = 0; i < path.length; ++i) {
    if ('..' === path[i]) {
      curr.pop();
    } else if ('.' != path[i] && '' != path[i]) {
      segs.push(path[i]);
    }
  }
  return curr.concat(segs).join('/');
};

/**
 * Register module at `path` with callback `definition`.
 *
 * @param {String} path
 * @param {Function} definition
 * @api private
 */

require.register = function(path, definition) {
  require.modules[path] = definition;
};

/**
 * Alias a module definition.
 *
 * @param {String} from
 * @param {String} to
 * @api private
 */

require.alias = function(from, to) {
  if (!require.modules.hasOwnProperty(from)) {
    throwError()
    return
  }
  require.aliases[to] = from;

  function throwError () {
    throw new Error('Failed to alias "' + from + '", it does not exist');
  }
};

/**
 * Return a require function relative to the `parent` path.
 *
 * @param {String} parent
 * @return {Function}
 * @api private
 */

require.relative = function(parent) {
  var p = require.normalize(parent, '..');

  /**
   * The relative require() itself.
   */

  function localRequire(path) {
    var resolved = localRequire.resolve(path);
    return require(resolved, parent, path);
  }

  /**
   * Resolve relative to the parent.
   */

  localRequire.resolve = function(path) {
    var c = path.charAt(0);
    if ('/' === c) return path.slice(1);
    if ('.' === c) return require.normalize(p, path);

    // resolve deps by returning
    // the dep in the nearest "deps"
    // directory
    var segs = parent.split('/');
    var i = segs.length;
    while (i--) {
      if (segs[i] === 'deps') {
        break;
      }
    }
    path = segs.slice(0, i + 2).join('/') + '/deps/' + path;
    return path;
  };

  /**
   * Check if module is defined at `path`.
   */

  localRequire.exists = function(path) {
    return require.modules.hasOwnProperty(localRequire.resolve(path));
  };

  return localRequire;
};