underscore源码解析（object）

//用来变对象的。可以没有value直接传list,把list变一个对象//也可以传长度和list一样的value，来构成数组_.object = function(list, values) {    var result = {};    for (var i = 0, length = list && list.length; i < length; i++) {        if (values) {            result[list[i]] = values[i];        } else {            result[list[i][0]] = list[i][1];        }    }    return result;};

//获取对象的所有键集合，有原生的nativeKeys,就用原生。//貌似ie9以下有个枚举bug，实例的toString会覆盖原型上的toString,toString就变成不可枚举了,都没试出来过。。。。//!({toString: null}).propertyIsEnumerable(‘toString‘);_.keys = function(obj) {    if (!_.isObject(obj)) return [];    if (nativeKeys) return nativeKeys(obj);    var keys = [];    for (var key in obj) if (_.has(obj, key)) keys.push(key);    // Ahem, IE < 9.    if (hasEnumBug) collectNonEnumProps(obj, keys);    return keys;};

// 所有键列出来，实例和原型的_.allKeys = function(obj) {    if (!_.isObject(obj)) return [];    var keys = [];    for (var key in obj) keys.push(key);    // Ahem, IE < 9.    if (hasEnumBug) collectNonEnumProps(obj, keys);    return keys;};

// 实例键的值组成一个数组_.values = function(obj) {    var keys = _.keys(obj);    var length = keys.length;    var values = Array(length);    for (var i = 0; i < length; i++) {        values[i] = obj[keys[i]];    }    return values;};

//类似map,只不过obj是对象，用iteratee迭代每个键值对，返回新数组_.mapObject = function(obj, iteratee, context) {    iteratee = cb(iteratee, context);    var keys =  _.keys(obj),        length = keys.length,        results = {},        currentKey;    for (var index = 0; index < length; index++) {        currentKey = keys[index];        results[currentKey] = iteratee(obj[currentKey], currentKey, obj);    }    return results;};

//把一个对象转变为一个[key, value]形式的数组。_.pairs = function(obj) {    var keys = _.keys(obj);    var length = keys.length;    var pairs = Array(length);    for (var i = 0; i < length; i++) {        pairs[i] = [keys[i], obj[keys[i]]];    }    return pairs;};

// 对象键值对互换位置，要保证键值对中值的唯一性_.invert = function(obj) {    var result = {};    var keys = _.keys(obj);    for (var i = 0, length = keys.length; i < length; i++) {        result[obj[keys[i]]] = keys[i];    }    return result;};//把对象中的函数堆到一个数组中，函数名按字母a-z排序_.functions = _.methods = function(obj) {    var names = [];    for (var key in obj) {        if (_.isFunction(obj[key])) names.push(key);    }    return names.sort();};//对象的扩展，扩展传入的所有属性，包括原型链_.extend = createAssigner(_.allKeys);

////对象的扩展，扩展传入的所有属性，不包括原型链_.extendOwn = _.assign = createAssigner(_.keys);