//now.jsvar root = require(‘./_root‘);//运行环境，node环境下为global,浏览器环境为window/** *  * * @returns {number} 得到一个时间戳. * @example * * _.defer(function(stamp) { *   console.log(_.now() - stamp); * }, _.now()); * // => Logs the number of milliseconds it took for the deferred invocation. */var now = function() {  return root.Date.now();//直接调用Date对象的now方法};module.exports = now;

//after.jsvar toInteger = require(‘./toInteger‘);//转化为整型/** Error message constants. */var FUNC_ERROR_TEXT = ‘Expected a function‘;/** *  * * @param {number} n 在调用func之前需要执行的次数. * @param {Function} func 受限制的方法. * @returns {Function} 返回新的受限制的方法. * @example * * var saves = [‘profile‘, ‘settings‘]; * * var done = _.after(saves.length, function() { *   console.log(‘done saving!‘); * }); * * _.forEach(saves, function(type) { *   asyncSave({ ‘type‘: type, ‘complete‘: done }); * }); * // => Logs ‘done saving!‘ after the two async saves have completed. */function after(n, func) {  if (typeof func != ‘function‘) {//如果不是函数，抛出TypeError    throw new TypeError(FUNC_ERROR_TEXT);  }  n = toInteger(n);//闭包中保存的n值  return function() {    if (--n < 1) {//每次执行n-1,如果比1小，调用func方法      return func.apply(this, arguments);    }  };}module.exports = after;

//ary.jsvar createWrap = require(‘./_createWrap‘);//包装函数var WRAP_ARY_FLAG = 128; //ary的位掩嘛/** *  * * @static * @memberOf _ * @since 3.0.0 * @category Function * @param {Function} func 需要包装的函数. * @param {number} [n=func.length] 参数个数. * @param- {Object} [guard] 是否能作为遍历参数被_.map这样的方法调用. * @returns {Function} 返回新的包装之后的函数. * @example * * _.map([‘6‘, ‘8‘, ‘10‘], _.ary(parseInt, 1)); * // => [6, 8, 10] */function ary(func, n, guard) {  n = guard ? undefined : n;  n = (func && n == null) ? func.length : n;//如果没传n,默认参数数量func的参数个数  return createWrap(func, WRAP_ARY_FLAG, undefined, undefined, undefined, undefined, n);//调用createWrap方法，并将结果返回}module.exports = ary;

//_createWrap.jsvar baseSetData = http://www.mamicode.com/require(‘./_baseSetData‘),    createBind = require(‘./_createBind‘),    createCurry = require(‘./_createCurry‘),    createHybrid = require(‘./_createHybrid‘),//创建混合方法    createPartial = require(‘./_createPartial‘),    getData = require(‘./_getData‘),    mergeData = require(‘./_mergeData‘),    setData = require(‘./_setData‘),    setWrapToString = require(‘./_setWrapToString‘),    toInteger = require(‘./toInteger‘);var FUNC_ERROR_TEXT = ‘Expected a function‘;//各种方法的位掩码标识var WRAP_BIND_FLAG = 1,    WRAP_BIND_KEY_FLAG = 2,    WRAP_CURRY_FLAG = 8,    WRAP_CURRY_RIGHT_FLAG = 16,    WRAP_PARTIAL_FLAG = 32,    WRAP_PARTIAL_RIGHT_FLAG = 64;var nativeMax = Math.max;//原生最大值方法/** * 创建一个函数，该函数可以创建或调用func用可选的this和部分应用的参数. * * @param {Function|string} func 需要包装的函数. * @param {number} bitmask 位掩码标识 * @param {*} [thisArg] . * @param {Array} [partials] . * @param {Array} [holders] . * @param {Array} [argPos] . * @param {number} [ary] . * @param {number} [arity] 可用参数数量. * @returns {Function} 返回包装之后的函数. */ //lodash使用BitMask来进行各种方法的表示，BitMask使用方法可以看 http://geek.csdn.net/news/detail/73343function createWrap(func, bitmask, thisArg, partials, holders, argPos, ary, arity) {  var isBindKey = bitmask & WRAP_BIND_KEY_FLAG;//是否是bindKey方法（不是，跳过）  if (!isBindKey && typeof func != ‘function‘) {    throw new TypeError(FUNC_ERROR_TEXT);  }  var length = partials ? partials.length : 0;//length=0  if (!length) {    bitmask &= ~(WRAP_PARTIAL_FLAG | WRAP_PARTIAL_RIGHT_FLAG);//清除WRAP_PARTIAL_FLAG和WRAP_PARTIAL_RIGHT_FLAG    partials = holders = undefined;  }  ary = ary === undefined ? ary : nativeMax(toInteger(ary), 0);  arity = arity === undefined ? arity : toInteger(arity);//处理一下arity  length -= holders ? holders.length : 0;  if (bitmask & WRAP_PARTIAL_RIGHT_FLAG) {//是否是WRAP_PARTIAL_RIGHT_FLAG(不是，跳过)    var partialsRight = partials,        holdersRight = holders;    partials = holders = undefined;  }  var data = http://www.mamicode.com/isBindKey ? undefined : getData(func);//得到func的元数据（没有，跳过）  var newData =http://www.mamicode.com/ [    func, bitmask, thisArg, partials, holders, partialsRight, holdersRight,    argPos, ary, arity  ];//将所有参数赋值给newData  if (data) {    mergeData(newData, data);  }  func = newData[0];  bitmask = newData[1];  thisArg = newData[2];  partials = newData[3];  holders = newData[4];  arity = newData[9] = newData[9] === undefined    ? (isBindKey ? 0 : func.length)    : nativeMax(newData[9] - length, 0);//再次处理一下arity  if (!arity && bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG)) {    bitmask &= ~(WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG);  }  if (!bitmask || bitmask == WRAP_BIND_FLAG) {    var result = createBind(func, bitmask, thisArg);  } else if (bitmask == WRAP_CURRY_FLAG || bitmask == WRAP_CURRY_RIGHT_FLAG) {    result = createCurry(func, bitmask, arity);  } else if ((bitmask == WRAP_PARTIAL_FLAG || bitmask == (WRAP_BIND_FLAG | WRAP_PARTIAL_FLAG)) && !holders.length) {    result = createPartial(func, bitmask, thisArg, partials);  } else {    result = createHybrid.apply(undefined, newData);//调用createHybrid方法，传入所有参数  }  var setter = data ? baseSetData : setData;//设置data的元数据（暂不分析）  return setWrapToString(setter(result, newData), func, bitmask);//给包装之后的方法添加元数据（用于优化），添加toStirng方法，并返回func(具体实现暂不分析)}module.exports = createWrap;

//_createHybrid.jsvar composeArgs = require(‘./_composeArgs‘),    composeArgsRight = require(‘./_composeArgsRight‘),    countHolders = require(‘./_countHolders‘),    createCtor = require(‘./_createCtor‘),    createRecurry = require(‘./_createRecurry‘),    getHolder = require(‘./_getHolder‘),    reorder = require(‘./_reorder‘),    replaceHolders = require(‘./_replaceHolders‘),    root = require(‘./_root‘);//位掩码标识var WRAP_BIND_FLAG = 1,    WRAP_BIND_KEY_FLAG = 2,    WRAP_CURRY_FLAG = 8,    WRAP_CURRY_RIGHT_FLAG = 16,    WRAP_ARY_FLAG = 128,    WRAP_FLIP_FLAG = 512;/** * 创建一个包装函数，调用func使用可选的thisArg，应用部分参数和柯里化. * * @param {Function|string} func 需要包装的方法. * @param {number} bitmask 位掩码标识 * @param {*} [thisArg] . * @param {Array} [partials] . * @param {Array} [holders] . * @param {Array} [partialsRight] . * @param {Array} [holdersRight] . * @param {Array} [argPos] . * @param {number} [ary] . * @param {number} [arity] 可用函数参数数量. * @returns {Function} 返回新的包装函数. */function createHybrid(func, bitmask, thisArg, partials, holders, partialsRight, holdersRight, argPos, ary, arity) {  var isAry = bitmask & WRAP_ARY_FLAG,//是否是ary（是的）      isBind = bitmask & WRAP_BIND_FLAG,      isBindKey = bitmask & WRAP_BIND_KEY_FLAG,      isCurried = bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG),      isFlip = bitmask & WRAP_FLIP_FLAG,      Ctor = isBindKey ? undefined : createCtor(func);  function wrapper() {    var length = arguments.length,//参数个数        args = Array(length),//保存所有参数        index = length;//参数数组索引    while (index--) {//遍历参数，将所有参数存入args      args[index] = arguments[index];    }    if (isCurried) {      var placeholder = getHolder(wrapper),          holdersCount = countHolders(args, placeholder);    }    if (partials) {      args = composeArgs(args, partials, holders, isCurried);    }    if (partialsRight) {      args = composeArgsRight(args, partialsRight, holdersRight, isCurried);    }    length -= holdersCount;    if (isCurried && length < arity) {      var newHolders = replaceHolders(args, placeholder);      return createRecurry(        func, bitmask, createHybrid, wrapper.placeholder, thisArg,        args, newHolders, argPos, ary, arity - length      );    }    var thisBinding = isBind ? thisArg : this,        fn = isBindKey ? thisBinding[func] : func;    length = args.length;//参数长度    if (argPos) {      args = reorder(args, argPos);    } else if (isFlip && length > 1) {      args.reverse();    }    if (isAry && ary < length) {//进入这里，将参数的长度缩减到ary的数量      args.length = ary;    }    if (this && this !== root && this instanceof wrapper) {      fn = Ctor || createCtor(fn);    }    return fn.apply(thisBinding, args);//调用func，并且传入的参数个数为ary个  }  return wrapper;}module.exports = createHybrid;

//before.jsvar toInteger = require(‘./toInteger‘);//转化为整型var FUNC_ERROR_TEXT = ‘Expected a function‘;/** * * * @param {number} n func不再被调用的执行次数上限. * @param {Function} func 需要限制的方法. * @returns {Function} Returns the new restricted function. * @example * * jQuery(element).on(‘click‘, _.before(5, addContactToList)); * // => Allows adding up to 4 contacts to the list. */function before(n, func) {  var result;  if (typeof func != ‘function‘) {//不是方法，抛出错误    throw new TypeError(FUNC_ERROR_TEXT);  }  n = toInteger(n);//还可以执行的n值  return function() {    if (--n > 0) {//如果n-1比0大,也就是n>=1,调用func,并将结果赋值给result      result = func.apply(this, arguments);    }    if (n <= 1) {//销毁func      func = undefined;    }    return result;//返回result  };}module.exports = before;

//bind.jsvar baseRest = require(‘./_baseRest‘),//生产具有rest参数的方法    createWrap = require(‘./_createWrap‘),//函数包装方法    getHolder = require(‘./_getHolder‘),//得到占位符标识    replaceHolders = require(‘./_replaceHolders‘);//替换占位符var WRAP_BIND_FLAG = 1,//bind位掩码    WRAP_PARTIAL_FLAG = 32;//partial位掩码/** *  * * _.bind.placeholder的值默认为`_` * * * @param {Function} func 需要绑定的函数. * @param {*} thisArg The func的this对象. * @param {...*} [partials] 提前传入的参数. * @returns {Function} 返回新的已绑定的方法. * @example * * function greet(greeting, punctuation) { *   return greeting + ‘ ‘ + this.user + punctuation; * } * * var object = { ‘user‘: ‘fred‘ }; * * var bound = _.bind(greet, object, ‘hi‘); * bound(‘!‘); * // => ‘hi fred!‘ * * // Bound with placeholders. * var bound = _.bind(greet, object, _, ‘!‘); * bound(‘hi‘); * // => ‘hi fred!‘ */var bind = baseRest(function(func, thisArg, partials) {  var bitmask = WRAP_BIND_FLAG;//位掩码为bind  if (partials.length) {//如果有传入参数    var holders = replaceHolders(partials, getHolder(bind));//得到占位符的索引    bitmask |= WRAP_PARTIAL_FLAG;//位掩码加上partial的标识  }  return createWrap(func, bitmask, thisArg, partials, holders);//调用createWrap方法，返回包装之后的方法});// 对默认的placeholder赋值.bind.placeholder = {};module.exports = bind;

//_createWrap.jsvar baseSetData = http://www.mamicode.com/require(‘./_baseSetData‘),    createBind = require(‘./_createBind‘),//创建bind方法    createCurry = require(‘./_createCurry‘),    createHybrid = require(‘./_createHybrid‘),    createPartial = require(‘./_createPartial‘),//创建部分参数方法    getData = http://www.mamicode.com/require(‘./_getData‘),    mergeData = require(‘./_mergeData‘),    setData = require(‘./_setData‘),    setWrapToString = require(‘./_setWrapToString‘),    toInteger = require(‘./toInteger‘);var FUNC_ERROR_TEXT = ‘Expected a function‘;//各种方法的位掩码标识var WRAP_BIND_FLAG = 1,    WRAP_BIND_KEY_FLAG = 2,    WRAP_CURRY_FLAG = 8,    WRAP_CURRY_RIGHT_FLAG = 16,    WRAP_PARTIAL_FLAG = 32,    WRAP_PARTIAL_RIGHT_FLAG = 64;var nativeMax = Math.max;//原生最大值方法/** * 创建一个函数，该函数可以创建或调用func用可选的this和部分应用的参数. * * @param {Function|string} func 需要包装的函数. * @param {number} bitmask 位掩码标识 * @param {*} [thisArg] func的this对象 * @param {Array} [partials] 应用的参数 * @param {Array} [holders] 占位符的索引 * @param {Array} [argPos] . * @param {number} [ary] . * @param {number} [arity] 可用参数数量. * @returns {Function} 返回包装之后的函数. */ //lodash使用BitMask来进行各种方法的表示，BitMask使用方法可以看 http://geek.csdn.net/news/detail/73343function createWrap(func, bitmask, thisArg, partials, holders, argPos, ary, arity) {  var isBindKey = bitmask & WRAP_BIND_KEY_FLAG;//是否是bindKey方法（不是，跳过）  if (!isBindKey && typeof func != ‘function‘) {    throw new TypeError(FUNC_ERROR_TEXT);  }  var length = partials ? partials.length : 0;//应用的参数个数，不传为0  if (!length) {    bitmask &= ~(WRAP_PARTIAL_FLAG | WRAP_PARTIAL_RIGHT_FLAG);//清除WRAP_PARTIAL_FLAG和WRAP_PARTIAL_RIGHT_FLAG    partials = holders = undefined;//部分参数和占位符索引都为undefined  }  ary = ary === undefined ? ary : nativeMax(toInteger(ary), 0);//没传，跳过  arity = arity === undefined ? arity : toInteger(arity);//跳过  length -= holders ? holders.length : 0;//如果有占位符，参数长度减去占位符长度  if (bitmask & WRAP_PARTIAL_RIGHT_FLAG) {//是否是WRAP_PARTIAL_RIGHT_FLAG(不是，跳过)    var partialsRight = partials,        holdersRight = holders;    partials = holders = undefined;  }  var data = http://www.mamicode.com/isBindKey ? undefined : getData(func);//得到func的元数据（没有，跳过）  var newData =http://www.mamicode.com/ [    func, bitmask, thisArg, partials, holders, partialsRight, holdersRight,    argPos, ary, arity  ];//将所有参数赋值给newData  if (data) {    mergeData(newData, data);  }  func = newData[0];  bitmask = newData[1];  thisArg = newData[2];  partials = newData[3];  holders = newData[4];  arity = newData[9] = newData[9] === undefined    ? (isBindKey ? 0 : func.length)    : nativeMax(newData[9] - length, 0);  if (!arity && bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG)) {    bitmask &= ~(WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG);  }  if (!bitmask || bitmask == WRAP_BIND_FLAG) {//如果没传partials，调用createBind方法，并且将包装函数赋值给result    var result = createBind(func, bitmask, thisArg);  } else if (bitmask == WRAP_CURRY_FLAG || bitmask == WRAP_CURRY_RIGHT_FLAG) {    result = createCurry(func, bitmask, arity);  } else if ((bitmask == WRAP_PARTIAL_FLAG || bitmask == (WRAP_BIND_FLAG | WRAP_PARTIAL_FLAG)) && !holders.length) {//如果传了partials，但是没有传占位符，调用createPartial方法，并且将包装函数赋值给result    result = createPartial(func, bitmask, thisArg, partials);  } else {//如果传了partials和holders，调用createHybrid方法    result = createHybrid.apply(undefined, newData);  }  var setter = data ? baseSetData : setData;//设置data的元数据（暂不分析）  return setWrapToString(setter(result, newData), func, bitmask);//给包装之后的方法添加元数据（用于优化），添加toStirng方法，并返回func(具体实现暂不分析)}module.exports = createWrap;

//_createBind.jsvar createCtor = require(‘./_createCtor‘),//创建一个可以创建函数实例的方法    root = require(‘./_root‘);//根元素，node环境为global,浏览器环境为windowvar WRAP_BIND_FLAG = 1;//bind位掩码标识/** * 创建一个包装func的方法，调用这个方法可以使用可选的this对象. * * @private * @param {Function} func 需要包装的函数. * @param {number} bitmask 位掩码标识. * @param {*} [thisArg] func的this对象. * @returns {Function} 返回新的包装函数. */function createBind(func, bitmask, thisArg) {  var isBind = bitmask & WRAP_BIND_FLAG,//是否是bind方法      Ctor = createCtor(func);//用于创建实例的构造器  function wrapper() {    var fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;//如果是根元素调用，使用func，否则使用Ctor    return fn.apply(isBind ? thisArg : this, arguments);//调用fn,传入this对象和参数  }  return wrapper;//返回wrapper方法}module.exports = createBind;

//_createPartial.jsvar apply = require(‘./_apply‘),//同Function.apply    createCtor = require(‘./_createCtor‘),//创建一个可以创建函数实例的方法    root = require(‘./_root‘);//根元素var WRAP_BIND_FLAG = 1;//bind方法位掩码/** * 创建一个func的包装方法，调用这个方法可以使用可选的this对象和提前传入部分参数. * * @private * @param {Function} func 需要包装的方法. * @param {number} 位掩码标识. * @param {*} thisArg func的this对象. * @param {Array} partials 提前传入的参数. * @returns {Function} 返回新的包装方法. */function createPartial(func, bitmask, thisArg, partials) {  var isBind = bitmask & WRAP_BIND_FLAG,//是否是bind方法      Ctor = createCtor(func);//用于创建实例的构造器  function wrapper() {    var argsIndex = -1,//参数索引        argsLength = arguments.length,//传入参数个数        leftIndex = -1,//提前传入参数索引        leftLength = partials.length,//提前传入参数个数        args = Array(leftLength + argsLength),//总参数        fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;//如果是根元素调用，使用func，否则使用Ctor    while (++leftIndex < leftLength) {//遍历partials,将参数作为调用方法的前面的参数      args[leftIndex] = partials[leftIndex];    }    while (argsLength--) {//遍历传入的参数，将其作为调用方法的后面的参数      args[leftIndex++] = arguments[++argsIndex];    }    return apply(fn, isBind ? thisArg : this, args);//调用fn,传入this对象和参数  }  return wrapper;//返回wrapper方法}module.exports = createPartial;

//_createHybrid.jsvar composeArgs = require(‘./_composeArgs‘),//组合参数方法    composeArgsRight = require(‘./_composeArgsRight‘),    countHolders = require(‘./_countHolders‘),    createCtor = require(‘./_createCtor‘),    createRecurry = require(‘./_createRecurry‘),    getHolder = require(‘./_getHolder‘),    reorder = require(‘./_reorder‘),    replaceHolders = require(‘./_replaceHolders‘),    root = require(‘./_root‘);//位掩码标识var WRAP_BIND_FLAG = 1,    WRAP_BIND_KEY_FLAG = 2,    WRAP_CURRY_FLAG = 8,    WRAP_CURRY_RIGHT_FLAG = 16,    WRAP_ARY_FLAG = 128,    WRAP_FLIP_FLAG = 512;/** * 创建一个包装函数，调用func使用可选的thisArg，应用部分参数和柯里化. * * @param {Function|string} func 需要包装的方法. * @param {number} bitmask 位掩码标识 * @param {*} [thisArg] this对象. * @param {Array} [partials] 实现传入的参数. * @param {Array} [holders] 占位符. * @param {Array} [partialsRight] . * @param {Array} [holdersRight] . * @param {Array} [argPos] . * @param {number} [ary] . * @param {number} [arity] 可用函数参数数量. * @returns {Function} 返回新的包装函数. */function createHybrid(func, bitmask, thisArg, partials, holders, partialsRight, holdersRight, argPos, ary, arity) {  var isAry = bitmask & WRAP_ARY_FLAG,      isBind = bitmask & WRAP_BIND_FLAG,//是否具有bind标识      isBindKey = bitmask & WRAP_BIND_KEY_FLAG,      isCurried = bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG),      isFlip = bitmask & WRAP_FLIP_FLAG,      Ctor = isBindKey ? undefined : createCtor(func);  function wrapper() {    var length = arguments.length,//参数个数        args = Array(length),//保存所有参数        index = length;//参数数组索引    while (index--) {//遍历参数，将所有参数存入args      args[index] = arguments[index];    }    if (isCurried) {      var placeholder = getHolder(wrapper),          holdersCount = countHolders(args, placeholder);    }    if (partials) {//执行composeArgs，对参数进行组合      args = composeArgs(args, partials, holders, isCurried);    }    if (partialsRight) {      args = composeArgsRight(args, partialsRight, holdersRight, isCurried);    }    length -= holdersCount;    if (isCurried && length < arity) {      var newHolders = replaceHolders(args, placeholder);      return createRecurry(        func, bitmask, createHybrid, wrapper.placeholder, thisArg,        args, newHolders, argPos, ary, arity - length      );    }    var thisBinding = isBind ? thisArg : this,//设置this为thisArg        fn = isBindKey ? thisBinding[func] : func;//设置fn为func    length = args.length;//参数长度    if (argPos) {      args = reorder(args, argPos);    } else if (isFlip && length > 1) {      args.reverse();    }    if (isAry && ary < length) {      args.length = ary;    }    if (this && this !== root && this instanceof wrapper) {      fn = Ctor || createCtor(fn);    }    return fn.apply(thisBinding, args);//调用fn，并且传入args  }  return wrapper;//返回包装方法}module.exports = createHybrid;

//composeArgs.jsvar nativeMax = Math.max;//原生求最大值方法/** * 创建一个由提前传入的参数，占位符和传入的参数组成的一维数组. * * @private * @param {Array} args 提供的参数. * @param {Array} partials 提前传入的参数. * @param {Array} holders 提前传入参数中的占位符索引. * @params {boolean} [isCurried] 指定是否组成一个柯里化函数. * @returns {Array} 返回新的参数集合. */function composeArgs(args, partials, holders, isCurried) {  var argsIndex = -1,//传入参数索引      argsLength = args.length,//参数个数      holdersLength = holders.length,//占位符个数      leftIndex = -1,//提前传入参数索引      leftLength = partials.length,//提前传入参数个数      rangeLength = nativeMax(argsLength - holdersLength, 0),//实际参数个数      result = Array(leftLength + rangeLength),//返回结果数组      isUncurried = !isCurried;//是否并未柯里化  while (++leftIndex < leftLength) {//遍历partials，将其传入result    result[leftIndex] = partials[leftIndex];  }  while (++argsIndex < holdersLength) {//遍历holders,将result中对应索引的值，换成传入的参数对应的值    if (isUncurried || argsIndex < argsLength) {      result[holders[argsIndex]] = args[argsIndex];    }  }  while (rangeLength--) {//遍历args，将剩余的参数传入reslut    result[leftIndex++] = args[argsIndex++];  }  return result;//返回生产的完整参数数组}module.exports = composeArgs;

//bindKey.jsvar baseRest = require(‘./_baseRest‘),//创建具有rest参数的方法    createWrap = require(‘./_createWrap‘),//函数包装方法    getHolder = require(‘./_getHolder‘),//得到占位符标识    replaceHolders = require(‘./_replaceHolders‘);//替换占位符var WRAP_BIND_FLAG = 1,//bind位掩码    WRAP_BIND_KEY_FLAG = 2,//bindKey位掩码    WRAP_PARTIAL_FLAG = 32;//partial位掩码/** * * * _.bind.placeholder的值默认为`_` * * @static * @memberOf _ * @since 0.10.0 * @category Function * @param {Object} object 调用该方法的对象. * @param {string} key 方法的key值. * @param {...*} [partials] 需要提前传入的参数. * @returns {Function} 返回新的已绑定的方法. * @example * * var object = { *   ‘user‘: ‘fred‘, *   ‘greet‘: function(greeting, punctuation) { *     return greeting + ‘ ‘ + this.user + punctuation; *   } * }; * * var bound = _.bindKey(object, ‘greet‘, ‘hi‘); * bound(‘!‘); * // => ‘hi fred!‘ * * object.greet = function(greeting, punctuation) { *   return greeting + ‘ya ‘ + this.user + punctuation; * }; * * bound(‘!‘); * // => ‘hiya fred!‘ * * // Bound with placeholders. * var bound = _.bindKey(object, ‘greet‘, _, ‘!‘); * bound(‘hi‘); * // => ‘hiya fred!‘ */var bindKey = baseRest(function(object, key, partials) {//创建使用rest参数的方法  var bitmask = WRAP_BIND_FLAG | WRAP_BIND_KEY_FLAG;//位掩码为bind和bindKey  if (partials.length) {//如果传入了partials    var holders = replaceHolders(partials, getHolder(bindKey));//得到占位符的索引    bitmask |= WRAP_PARTIAL_FLAG;//位掩码加上partial的标识  }  return createWrap(key, bitmask, object, partials, holders);//调用createWrap方法，返回包装之后的方法});// Assign default placeholders.bindKey.placeholder = {};module.exports = bindKey;

//_createWrap.jsvar baseSetData = http://www.mamicode.com/require(‘./_baseSetData‘),    createBind = require(‘./_createBind‘),//创建bind方法    createCurry = require(‘./_createCurry‘),    createHybrid = require(‘./_createHybrid‘),    createPartial = require(‘./_createPartial‘),//创建部分参数方法    getData = http://www.mamicode.com/require(‘./_getData‘),    mergeData = require(‘./_mergeData‘),    setData = require(‘./_setData‘),    setWrapToString = require(‘./_setWrapToString‘),    toInteger = require(‘./toInteger‘);var FUNC_ERROR_TEXT = ‘Expected a function‘;//各种方法的位掩码标识var WRAP_BIND_FLAG = 1,    WRAP_BIND_KEY_FLAG = 2,    WRAP_CURRY_FLAG = 8,    WRAP_CURRY_RIGHT_FLAG = 16,    WRAP_PARTIAL_FLAG = 32,    WRAP_PARTIAL_RIGHT_FLAG = 64;var nativeMax = Math.max;//原生最大值方法/** * 创建一个函数，该函数可以创建或调用func用可选的this和部分应用的参数. * * @param {Function|string} func 需要包装的函数. * @param {number} bitmask 位掩码标识 * @param {*} [thisArg] func的this对象 * @param {Array} [partials] 应用的参数 * @param {Array} [holders] 占位符的索引 * @param {Array} [argPos] . * @param {number} [ary] . * @param {number} [arity] 可用参数数量. * @returns {Function} 返回包装之后的函数. */ //lodash使用BitMask来进行各种方法的表示，BitMask使用方法可以看 http://geek.csdn.net/news/detail/73343function createWrap(func, bitmask, thisArg, partials, holders, argPos, ary, arity) {  var isBindKey = bitmask & WRAP_BIND_KEY_FLAG;//是否是bindKey方法（是的）  if (!isBindKey && typeof func != ‘function‘) {    throw new TypeError(FUNC_ERROR_TEXT);  }  var length = partials ? partials.length : 0;//应用的参数个数，不传为0  if (!length) {    bitmask &= ~(WRAP_PARTIAL_FLAG | WRAP_PARTIAL_RIGHT_FLAG);//清除WRAP_PARTIAL_FLAG和WRAP_PARTIAL_RIGHT_FLAG    partials = holders = undefined;//部分参数和占位符索引都为undefined  }  ary = ary === undefined ? ary : nativeMax(toInteger(ary), 0);//没传，跳过  arity = arity === undefined ? arity : toInteger(arity);//跳过  length -= holders ? holders.length : 0;//如果有占位符，参数长度减去占位符长度  if (bitmask & WRAP_PARTIAL_RIGHT_FLAG) {//是否是WRAP_PARTIAL_RIGHT_FLAG(不是，跳过)    var partialsRight = partials,        holdersRight = holders;    partials = holders = undefined;  }  var data = http://www.mamicode.com/isBindKey ? undefined : getData(func);//得到func的元数据（没有，跳过）  var newData =http://www.mamicode.com/ [    func, bitmask, thisArg, partials, holders, partialsRight, holdersRight,    argPos, ary, arity  ];//将所有参数赋值给newData  if (data) {    mergeData(newData, data);  }  func = newData[0];  bitmask = newData[1];  thisArg = newData[2];  partials = newData[3];  holders = newData[4];  arity = newData[9] = newData[9] === undefined    ? (isBindKey ? 0 : func.length)    : nativeMax(newData[9] - length, 0);  if (!arity && bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG)) {    bitmask &= ~(WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG);  }  if (!bitmask || bitmask == WRAP_BIND_FLAG) {//    var result = createBind(func, bitmask, thisArg);  } else if (bitmask == WRAP_CURRY_FLAG || bitmask == WRAP_CURRY_RIGHT_FLAG) {    result = createCurry(func, bitmask, arity);  } else if ((bitmask == WRAP_PARTIAL_FLAG || bitmask == (WRAP_BIND_FLAG | WRAP_PARTIAL_FLAG)) && !holders.length) {    result = createPartial(func, bitmask, thisArg, partials);  } else {//进入这里，调用createHybrid方法。    result = createHybrid.apply(undefined, newData);  }  var setter = data ? baseSetData : setData;//设置data的元数据（暂不分析）  return setWrapToString(setter(result, newData), func, bitmask);//给包装之后的方法添加元数据（用于优化），添加toStirng方法，并返回func(具体实现暂不分析)}module.exports = createWrap;

//_createHybrid.jsvar composeArgs = require(‘./_composeArgs‘),//组合参数方法    composeArgsRight = require(‘./_composeArgsRight‘),    countHolders = require(‘./_countHolders‘),    createCtor = require(‘./_createCtor‘),    createRecurry = require(‘./_createRecurry‘),    getHolder = require(‘./_getHolder‘),    reorder = require(‘./_reorder‘),    replaceHolders = require(‘./_replaceHolders‘),    root = require(‘./_root‘);//位掩码标识var WRAP_BIND_FLAG = 1,    WRAP_BIND_KEY_FLAG = 2,    WRAP_CURRY_FLAG = 8,    WRAP_CURRY_RIGHT_FLAG = 16,    WRAP_ARY_FLAG = 128,    WRAP_FLIP_FLAG = 512;/** * 创建一个包装函数，调用func使用可选的thisArg，应用部分参数和柯里化. * * @param {Function|string} func 需要包装的方法. * @param {number} bitmask 位掩码标识 * @param {*} [thisArg] this对象. * @param {Array} [partials] 实现传入的参数. * @param {Array} [holders] 占位符. * @param {Array} [partialsRight] . * @param {Array} [holdersRight] . * @param {Array} [argPos] . * @param {number} [ary] . * @param {number} [arity] 可用函数参数数量. * @returns {Function} 返回新的包装函数. */function createHybrid(func, bitmask, thisArg, partials, holders, partialsRight, holdersRight, argPos, ary, arity) {  var isAry = bitmask & WRAP_ARY_FLAG,      isBind = bitmask & WRAP_BIND_FLAG,//是否具有bind标识（有）      isBindKey = bitmask & WRAP_BIND_KEY_FLAG,//是否具有BindKey标识（有）      isCurried = bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG),      isFlip = bitmask & WRAP_FLIP_FLAG,      Ctor = isBindKey ? undefined : createCtor(func);  function wrapper() {    var length = arguments.length,//参数个数        args = Array(length),//保存所有参数        index = length;//参数数组索引    while (index--) {//遍历参数，将所有参数存入args      args[index] = arguments[index];    }    if (isCurried) {      var placeholder = getHolder(wrapper),          holdersCount = countHolders(args, placeholder);    }    if (partials) {//执行composeArgs，对参数进行组合      args = composeArgs(args, partials, holders, isCurried);    }    if (partialsRight) {      args = composeArgsRight(args, partialsRight, holdersRight, isCurried);    }    length -= holdersCount;    if (isCurried && length < arity) {      var newHolders = replaceHolders(args, placeholder);      return createRecurry(        func, bitmask, createHybrid, wrapper.placeholder, thisArg,        args, newHolders, argPos, ary, arity - length      );    }    var thisBinding = isBind ? thisArg : this,//设置this为thisArg        fn = isBindKey ? thisBinding[func] : func;//设置fn为thisBinding[func]    length = args.length;//参数长度    if (argPos) {      args = reorder(args, argPos);    } else if (isFlip && length > 1) {      args.reverse();    }    if (isAry && ary < length) {      args.length = ary;    }    if (this && this !== root && this instanceof wrapper) {      fn = Ctor || createCtor(fn);    }    return fn.apply(thisBinding, args);//调用fn，并且传入args  }  return wrapper;//返回包装方法}module.exports = createHybrid;